If one didn't know we are friends, they might think we're sparring...
Throw in the 1.5-2lbs for the regulator, and that 4.4lbs shrinks....
From a practical standpoint, diving my AL80 doubles I am weighted perfectly... Carrying multiple aluminum deco bottles through the course of the dive has had negligible impact on my buoyancy.
Since we're talking a bailout scenario, you have two fundamental situations in front of you... your either on a fixed line attached to the wreck, to which you can hang on the line.... or your drifting under a bag on deco, drain the bottle and send it up....
The key item I think to drive home here is that these bottles are dynamic, they are not fixed to your rig, as such you need to be able to maintain buoyancy w/o them, should you need to ditch at some point.... The characteristics of steel impose a far greater dynamic shift than aluminum.
The swing from empty to full is really splitting hairs; gas under pressure weighs roughly the same per volume, i.e. 3-5lbs for the volumes we're talking