Jon, teflon isn't for sealing on threads, it's to basically lubricate while they're being tightened. Typically used for brass or especially SS where they will burr or on NPT threads where they are tapered.
Stuart, the angle adapters swivel, identical to the connection on the hose.
I use them on bungeed octo's to allow me to use a shorter hose and it keeps it from bowing which I don't like. Not an issue in use but they can flop around a bit during setup. I keep a bolt snap on the regulator side of the adapters so I can clip everything off. I use 90*'s and ball swivels.
I prefer the 40" hose to 5' for open water diving. I think 5' hoses are pretty useless personally. I'm a tall diver, so if I'm diving with someone with a 5' hose we can't go single file, 7' hoses are actually pushing it for comfort. the 40" with an angle adapter allows you to dive next to each other, little cozy, but it works if you have to move around. 5' hose allows you a bit more wiggle room next to each other, but still can't go single file which is why a 7' minimum is required for overhead environments.
Some people who don't know how to think will suggest using a 5' hose for short divers because the 7' is too long, but this is directly analogous to divers with low SAC rates using smaller tanks because they use less air, real bad idea. Yes I have seen this justification in overhead environments.... If you don't like tucking the hose into your waist band, and aren't diving with a canister, Deep Sea Supply makes a super cheap *$15* canister blank for holding the long hose down, or you can use a knife on that side for the same thing. Moral of story is that unless you have an aversion to using the angle adapters, or are taking GUE training, the 40" hose on an angle adapter has been used for well over a decade by many technical divers in openwater environments with great success.
