OP, just get the Atomic B2 set or a Scubapro G260 with a Mark 25 Evo first or if budget is a concern the Hog sets are nice.
As to unbalanced first stages, there is much to be said for simplicity and reliability. They just work and keep on working no matter what. The drop in performance as pressure decreases in the tank, thus a drop in IP, is not that big of a deal if the second stages are a good, simple, reliable balanced design, like a G250 or G260 or similar. I have used such regs at depth, under strenuous conditions and was just fine.
My newest regulator, picked up the Mk 2 Evo for a song in Bonaire, always wanted my own, and just prepped it for my next trip. I meant it as a reliable back up but it may become the go to for the trip as I need to travel light and reliability is priority. Is it not a beauty:
A standard tank valve can flow about 40 cfm wide open. No currently produced regulator from any manufacturer I know of cannot flow at least double if not multiples of that volume. And volume is the key word because the volume is the same at depth as it is at the surface and within sport diving depths (and then some) the increase in density is real but not enough to reduce the volume the regulator can flow significant to the diver. Decades ago I used Mk 2s with unbalanced second stages at depths I should never have been at spearing fish offshore Louisiana. It was stupid and dangerous and very strenuous. A relative was bent and paralyzed doing a similar thing. But the Mk 2 and the unbalanced second stages did just fine.
A scuba valve can flow about 40 cfm wide open. A top performing second stage can flow about 60 cfm wide open. A top performing human body at maximum output can flow about 4 cfm (an elite athlete may can flow about 8 cfm). That is a lot of ventilation. Strap a tank to your stationary bike or treadmill/elliptical and see how fast you breath it down with you going full out. My point is to not get lost in the numbers, any modern regulator set or any from even decades past can deliver all the air volume you will ever need at any reasonable depth you belong at. So purchase the pretty one (Atomic) the ugly one (Scubapro G260) or the one you can gets parts for or from the lds who smiles the nicest at you or just toss a coin. Nowadays, I prefer the ones that have the
S on them.