I'd buy (and have tiwice) an Atomic also. A B2 is $730 and has a standard 2 year or 300 dive service interval. Fundamentally the difference is the material used - performance is the same. The Z designation is Zirconium plated Brass - a B2 will have more Titanium components in it's construction. Their flaghip T3 model ($1700) is all Titanium which does not rust or corrode - ever.
Pair it with a Z2 Octo which breathes the same as the B2 2nd so no reason to match 2nds. A Z2 with a standard hose is $290 in yellow or other colors.
Or the SS1 Octo Inflator is $299 if you like that approach.It's also built to breathe the same since it's
your reg when you donate your primary in an air-share situation. A buddy is happy with his.
All the Atomic 2nds breathe the same by design. So the idea of a "cheaper octo" expressed above in terms of performance is not true. In the Atomic line the more expensive models are made with more exotic metals so that's the price difference.
If you want the B2 sealed (for colder or siltier conditions) it's $40 more at purchase.
Deep6's sales model includes sending it back to them in GA when it needs service or finding a tech locally whose insurance allows them to use the provided Deep6 parts kit to service your reg. Good option if you plan to DIY reg servicing now or in the future.
I also like Aqualung Legends - they have a lot of service locations worldwide if needed. They have a 1st year inspect/2nd year service policy and if you miss it, your warranty goes with it.
If Scubapro is of interest, a Mk25/S600 is $729. with a G260 2nd it's $739. One of the highest performing regulators ever made.
An S550 2nd is another $300, an R195 is S189. Keeping the reg all the same brand makes it easier to service at one location. I came within about an hour of buying a Mk25/S600 once until my dealer showed me the Atomics. 2 year service interval is standard now on Scubapro models also.
I want a super smooth, breaths like budda regulator. Lots of air flow and super easy breathing to the point I cant even tell I'm breathing out of a regulator.
For me that's Atomic with the
2nd stage swivel. A couple times now while filming, I've almost dropped the reg. out of my mouth since I'm barely holding it in place and breathing effortlessly thru it.