Man it took a while, but this thread sure has taken off! As a "for the record" type post, yeah, the Vltor stocks have battery sotrage just like the Crane. It also has the same type cheek weld. Im wondering what it was about the Crane the original poster liked that he did not find in the Vltor?
Also, 5.56 in a handgun will not produce sufficient volocity for the ammo to do what it has to do. The 5.5 is an AWESOME round, even in CQB, for all the reasons stated by those who are promoting it. BUT(!) it requires sufficient volocity to do that. An AR handgun, or other handgun that fires 5.56 ammo will not allow the round to build up sufficient volocity for it to be a good choice as a handgun round. Without velocity, you are making .22 cal holes. No good.
Put it in a rifle, even a short barrel rifle, with say a 10.5" or 11.5" barrel, and you have sufficient volocity to have the round do what it does best at least for common indoor distances. Put it in a 14.5" or 16" carbine and it will do it out to common urban distances indoor or out.