@Arioc
so i'll start with the rig. The SMS100 is terrible, if you go that route, go with the SMS75, it's what the SMS100 should have been. Even though you aren't in the US, it would be good to call Edd and you might be surprised, especially depending on which tropical destination you are going to. The SMS75 will accept a backmounted single with no issues.
The Nomad XT works very well and doesn't actually need a butt plate, especially with aluminum tanks, however it does really need the Nomad wing. It is designed to go underneath the backplate and because of that, you need a wing designed to fit around it otherwise it gets weird. If you get a Nomad XT, just remove the butt plate because it will get in the way with single tank diving, and is completely unnecessary with AL80's. That Soprasub looks snazzy though
Regarding regulators.
@DevonDiver and I are going to have to disagree greatly on this, so sorry Andy.
I agree that a swivel turret is better, however I generally disagree about the bottom port, though it is always better to have and not need than to need and not have.
I own at least a dozen sets of Poseidon Jetstreams and a pair of Cyklons. The Cyklons are annoying because there is no affordable option to go with a normal hose without going to Omniswivel. Cyklons do not need overpressure relief because they are a standard downstreamd esign, their custom hose is because it's a slightly different fitting than the normal regulator hoses. With the Jetstreams, as long as they have the 3960 first stage or newer, the OPV is built into the bottom of the first stage, and with a very inexpensive adapter from Dive Gear Express or XS Scuba *or the expensive ones from Omni*, you can use standard hoses, which I do for all of my sidemount/stage regulators. Poseidon has one as well, but I don't know how expensive it is. The ones from XS or DGX are just fine if you don't need the OPV. The only sets that don't have them are my dedicated singles and dedicated doubles sets because I haven't had a need to place an order with DGX in several months. I do use ball swivels on all of my sidemount regs, but it's a comfort thing, it's obviously not necessary.
I find hose routing to be just as streamlined with these as my buddies with swivel turrets with the only two disadvantages being that the long hose reg is annoying at the surface because the HP hose goes in the other direction of the LP hoses, and there is a somewhat higher risk of it getting kinked off during a single file air share. As this is purely recreational diving, it's a non-issue.
Feathering is possible on these regulators, I have done it, but more importantly, in the event of a HP seat failure, they are much easier to breathe and work with than normal regs. With a normal reg, the freeflow starts and the venturi effect will start forcing it to freeflow harder and harder. On the Poseidons, because they are a semi-upstream design, in the event of a HP seat failure, the overpressure will be released either at the hose fitting if using the Poseidon hoses or the Omni swivels with the release built in, or at the first stage. When this happens, the regulators are still going to breathe as normal, just with a bit of an increased work of breathing. Pros and cons, though I choose to use an IP gauge regularly to minimize the risk of it showing up in the water to begin with.
Service and spares globally is annoying, but shouldn't be any more expensive than Scubapro/Apeks and Poseidon has the advantage to those two of actually allowing divers to take the service course and purchase parts and kits freely. That alone is reason enough for me not to recommend Apeks or Scubapro, especially for any dive professionals or technical divers. Ironically, Poseidon requires less specific tools than Scubapro does, though Apeks does win for the least amount of specific tools required. For Poseidon, aside from the big ass wrench to get the top of the first stage off, the only "special" tool required is a bic pen *one of the o-rings inside the second stage, but I've never heard of that one failing, and it's more highly recommended than required. It can be done with allen keys and an o-ring pick, it's just a special kind of annoying* and preferably a set of metric allen keys with the balls on the bottom *to remove the HP seat*. Apeks only needs the pin spanner and allen keys. It is nicer/easier if you have the tools, but you can successfully rebuild both stages with just a set of allen keys, and the big wrench to open up the first stage if you're patient.
The Jetstream/Xstreams can also go onto any first stage as long as the IP is adjusted to ~125psi/8.5bar, and you put an OPV on it, either using a Poseidon hose with the relief, the Omni Swivel adapter, or a cheap $3 OPV that people use on argon bottles and what not.
This is the omni swivel that is epic. Ball swivel, normal hose adapter, and OPV built into one. Not cheap by any means, but really really nice and it is compatible with the Xstream and Jetstream
Omni Swivel Poseidon Xtreme Swivel | Dive Right In Scuba - Plainfield, IL - Dive Right in Scuba
Poseidon has the extra advantage of being non-directional. I run my long hose from the right and instead of hog looping it, it crosses behind my neck onto my left side. I "know" which bottle I'm breathing off of because of which side the bubbles are coming off of, it keeps my shoulders balanced in terms of clutter, and reduces snag hazards when in sidemount passages. When air sharing, instead of having to rotate the reg about the vertical axis, you rotate it along the horizontal axis *mouthpiece down then forward* which reduces hose bending during air sharing and also helps to keep as much air inside the reg body as possible to help with clearing. Reversible regs can't do that since they are fixed from one side or the other which can lead to hose crossing in an overhead. When gearing up, I am able to clip both second stages to my chest d-rings and breathe off of them "reversed" from where I normally would until I get horizontal in the water so there is no undue pressure on the reg hoses until the bottles get situated when horizontal. This one isn't a huge benefit, but it's an added perk since I don't cross hoses/put the suicide strap on until I'm horizontal and everything is riding where it is supposed to.
Halcyon regs are made by Scubapro fwiw, and UTD's are made in Taiwan by I believe ODS who also makes HOG, Deep6, and a myriad of other regulators. Good regs, but I would never buy UTD branded ones. Deep6 currently has the best regulators made by ODS and have the advantage of coming with their first parts kit and first service is free, albeit it is done in the US which would be annoying.
Regarding the Apeks. If you're buying Apeks, it is worth holding out for a set of DST's over DS4's. While I don't have enough of an issue with not having one to spend a bunch of money to replace my first stages, I really wouldn't recommend for new sidemount divers to buy regs without one. The Apeks do not come with the fifth port on the bottom as standard, but that's not nearly as important as the swivel in most circumstances. The fifth port is nice if you front mount your bottles like the Razor crowd so you have a more direct hose routing, but if the bottles are truly sidemounted, then the fifth port is counterproductive.
This is my long hose side using Poseidon Jetstreams with the 3960 first stage, Hollis Katana, and PST HP120's. The swivel wouldn't gain me anything at this point, however if I had to share air, I would have to make sure that I don't allow the long hose to kink if the idiot in front of me pulls too hard. Similar to when diving backmount, you just hold onto the hose to make sure they can't pull it out. The fifth port, would be counterproductive because it would shove the inflator straight into my rib cage which isn't exactly streamlined. In this case, it is a standard length drysuit inflator that comes back up to my drysuit. On the other side, both hoses go straight up and directly into where they are supposed to.
Rigged, they look like this. Was experimenting on that trip with SPG's down, hated it, and have since switched back to SPG's up like in the picture above.
I don't like elbows, but others don't like ball swivels, so to each his own. I've seen too many elbows shoot off where the threads stripped and only one ball swivel separate which was my dumba$$ fault for not putting loctite on the screw like you're supposed to. Edd has several thousand dives on his with no issues, and the issues I hear about are those from people who don't rebuild the swivels when they rebuild their regulators, and if they did, were an idiot like I was and rebuilt them improperly. The elbows, there isn't anything you could have done if that screw wants to strip and shoot the elbow in half.
To each his own, but I wouldn't be so quick to write Poseidon off
