The lift bag idea is the most ridiculous of all. Do you really think you'll be able to get out and fill a lift bag as you're lawn-darting to the bottom?
The short answer to all this is al80s with the wetsuit, drysuit with everything else, and stay away from dual bladder wings and lift bags. Balanced rig and all that.
In fact, the lift bag redundancy was the solution employed by tech instructor, Andre Smith, in the Divers Supply Tripple Death Tragedy some maybe remember reading about in the late 90's. Andre and 3 students, all geared with heavy steels and stages, and using wet suits on a 280 foot deep dive....One student could not get neutral on the bottom, as his bungie wing kept letting air out through the OPV, before he could get enouhg air in the wing to get neutral.....Andre was heavy himself, and after the first mentioned student ran OOA and drowned on the bottom( without Andre offering him gas), Andre tried to get off the bottom by deploying a lift bag...which got away from him, leaving him too heavy to get off the bottom...There was one single surviver, so we actually know what happened. Andre ended up stripping his doulbles off and attempting a free ascent, but did not make it.
A "balanced rig" would have saved each of them. Dry suits instead of wetsuits would have saved each. The thick wetsuits with heavy steel was stupid. PADI needs to get their collective heads out of their asses and call bad gear combos, bad.....rather than coming up with nonsense like double bladders.
As a P.S... I also just remembered that the survivor also recounted that they were all suffering from hyperthermia on the dive, and he and Claypool barely had the strength left in their legs from this, to swim up to the shallower, warmer water.
Doing the 280 foot deep dives off of Palm Beach in the 90's, we began this with wet suits, but abandoned this after a few months( of course we used balanced rigs even then) because almost 1 third of the dives we would do in the summer would need to be aborted--it would be warm on the surface, but at 200 or so their would be an inversion or something going on, and the temp would be closer to high 50's. You could feel your feet almost instantly dissappearing/going numb, leaving you kicking your knees to make the fins push. In fact, in those early days, I would use a lycra suit as often as a wet suit, since at depth there was almost no difference in warmth. Deco would put the warmth advantage to the wet suit, but the entire bottom time the lycra was nicer because you could use almost no weight at all, so you had very nice bpuyancy and trim simplicity.
We switched to dry suits because having to cancel / abort a dive after all the planning and nonsense time wasting of doing a deep dive day like this, was very annoying.
