I've noticed that white has a 3-2 win advantage over black in all of the games so far for BB+. As a possibility to make things a little more fair for black, I propose the following:

On turn 1, white gets 1 shot, black gets 2 shots
On turn 2, white gets 3 shots, black gets 4 shots
On turns 3 and after, both sides get 5 shots.

Perhaps this could be another variant, or it could just supplant the existing rules for BB+ (I see the former as being the most likely)