I would like to point out here that my class was by PADI and that is one of the skills that was stressed by my instructor, in fact he would not pass you if you could not disconnect inflator, right yourself from a head down position, pull open a neck seal, with gloves and hood on, reconnect, and return to a hover .... all this without reaching the surface from starting at 8 feet, and after the instructor held the inflate valve on your suit for the count of three before letting you go. ... http://www.scubaboard.com/forums/advanced-scuba-discussions/260824-padi-dry-suit-class.html....
One big issue they don't touch on is dealing with a runaway ascent. If you have a big bubble in the suit and you find yourself ascending too quickly the valve might not be able to vent quick enough - result, burping the neck seal and possible flooding. I haven't had that problem but I have seen others flood just that way.
With a smaller bubble in the DS the valve can keep up and the BC can dump air far faster than the DS.
All this is just my experience and I'm not disagreeing with PADI, I keep spending money there. It's their agency and they can make their rules any way they want but, I have to admit... I don't wear a snorkel on my mask either :shocked2:
One other reason to train with just suit for buoyancy is that with more air in your suit, it's touchier on trim and air transfer ... if you can learn to handle with it that way, then with less air it will be easier
Edit: sorry for the hijack