Hmmm ... now I'm gonna have to test that theory. I'm not convinced it's as bad as you claim ... in fact, I'm fairly sure it's not. As for ascending unbalanced ... I'm certain that is a non-issue. And once on the surface, what do I need the gas in my cylinders for? I've got cubic miles of breathable gas. In a pinch, I'd dump the other tank and swim to boat or shore. Without tanks, I'm damn sure not gonna sink and drown.
How do I think that story ends? I swim in, grab another rig, and go retrieve my cylinder(s).
Again, I'm not saying redundant buoyancy ain't the best solution ... but I think you're overstating the "danger" of dumping a tank ... and it'd be interesting to find out who's right.
I'll give it a try tomorrow and let ya know how it works out ...
... Bob (Grateful Diver)