Now, Tim. Neutral at the end of a dive (1/3 remaining) and a balanced rig are two different things. What you estimate your negative to be at the beginning of the dive. I'm guessing:
Tanks x2 ............... -4
Manifold ................ -4
Tank Bands ........... -2
AL BP ................... -2
AL40 .................... -3
Can Light .............. -2
Jets ..................... -1
Misc gear .............. -1
3mm ws (170fsw) ... +1
Total .................... -18
Under stress, I'd love to see you swim up 18 pounds off the bottom and hold stops. For anyone with a high lean muscle mass to fat ratio, it gets even worse. And, you'd better hope you don't experience a leg cramp, because you can't stop kicking.
In this case, it is not a balanced rig. If it was less than 8-10 lbs, I'd give you that. I guess 'balanced' rig is subjective, but at this depth, the 3mm gives no help. Now, on a shallow recreational dive with a single tank and standard fundies gear, absolutely it's more than likely balanced and swimable. If not, there is something wrong with the choice of gear.
This is why the conversation was started in the first place. There are dives where 'balanced' isn't possible, and the need for redundant bouyancy is a neccessity. In that case, what are the preferred options? Dual bladder wing, drysuit, and LB's all make good solutions, some better than others. The LB being the least desirable but still doable and cheapest solution. And it answers the original poster's question.
