I've been diving with a Ballance for about 300 dive now. It's ok, but I never really liked it that much. My wife dove with a SeaQuest Diva for a bunch of years too. I got her a ScubaPro Bella last summer. It's far, far superior. Night and day. I'm going to get myself either a Night Hawk or Glide Pro next week. I've used a back inflator system for many years but don't know if it really makes any difference. If I stop kicking and just hover while wearing the Ballance, I quickly rotate vertical with my head up. My wife stays horizontal with her jacket system??? Maybe I have heavy feet. On the surface, it holds my head in the water. What's the point of a back inflate system if it doesn't hold me horizontal UW? One thing that I really like much better on the Scuba Pro is the three way air dump. It's a pain to dump air on the Ballance and you need to be really limber to reach the pull string on the back. The dump on my wife's Bella is great and it's the same on the men's unit. I won't dive with the new one until my next trip in May though. The only drawback is that the SPs are bigger when packing.
Hope that helps.