Volume wouldnt be a problem in the least. While it would sound better...as more speakers sounds better but there not gonna touch a 4 12 in terms of bass thumping power...no way to get around it. Some bonus's however with 2x12 cabs is that you can get different speaker combos, easier to carry, the are closed back so does give more thump then an open cabnet. I dont know how to run a 2 12 combo and a 2 12 cabnet however...might take some ohm switching. My personal opinion is go with the 2 12 cabnit, i think its very advantagous for rock music to have a closed back. Do not get tied up into the whole 4 12 stack is the "best" debate...while i can see that once upon a time where there were a lack of in house p.a. systems or out door gigs, anything less then a medium sized venue is kinda like killing a fly with a bazooka, too much. And if the day arises where your get a large enough venue, you can mic it. I know, know, it looks cool...but damn if my back gives to ****s about that.

The best situation is to RENT a 4 12 for 1 weekend ...beleive me its worth it and then rent a 2 12 and use that. make sure you gig with it.

Im one for a nice 2 12 cabnet, but then again my Marshall jcm Slash has some thunderous bass..so .. but i think the tsl has descent bass as well, but i ve been told it can get a little tubby pushing a 4 12.

A perfect case in point is SRV. He has the greatest tone of all time...so thick, full, and really sticks to your ribs. He did it through a 4 10 and 1 15 open back fender amps. His trick was IMMENSE volume. Later he got 200W super marshalls to get the cleanest sound at the highest volumes but by that time his tone kinda degraded to a more synthetic like SRV tone...