On the Zeagle you can mount their wings, from 35# on up, as well as any wing made for 11" grommets. You can mix and match the lower part of the BC with differnt sized and styled shoulder harnesses and wing sizes. The 44# wing is pretty big, and has quite a bit of drag, your dealer can get it for you with the 35# wing which should be enough.
I just got a 30# OxyCheq wing that fits my Ranger if I don't use it on my BP.
The DiveRite's weight pouches are actually pretty good, unlike the Zeagle's they can be moved back and forth along the harness, or used with a seperate belt. They're supposed to sit on the metal plates that come from the shoulder harness, but with keepers will work anywhere, great for balancing. They have quick release velcro openings on the bottom, and zippers for loading on top. Good combo as you don't wear out the velcro everytime you go diving. DiveRite's 30# travel wing is circular which I prefer over the horseshoe shaped Zeagle bladders. Again, anything with 11" grommets will fit.
DiveRite offers alu & ss backplates that'll slide into the transpak's harness, kinda like the OMS does. That'll add stability, though not quite as much as just a backplate.
Zeagle started selling ss and titanium bp, I'm not sure how well they fit between padding and the Ranger.
When you get into doubles you'll probably end up using bp/w anyway, so if you get a chance try one.
Either way, in my experience either manufacturer offer top notch quality and customer service.
PS: I never tried the Concept, but it uses a different modular system (PFS II).
The Ranger, Escape, Scout, Tech etc. all use the PFS I, and parts are interchangable.