OP- if you're just using your cab as a monitor spend your money on a nice amp (like the GK) that has a good-sounding DI and get a LOUD cabinet.
Let the big multi-way system out front do the heavy lifting, and don't go thinking you might want that kind of sound reproduction for yourself, too. You can make do with the same thing everybody else uses.
Also, other thing to consider is not everyone (including me) likes loud from little boxes. Lifting heavy objects proves you can lift heavy objects. There's a reason nobody touring for anything remotely heavy uses 10x115 setups like people are suggesting. They use 10 & 115 setups like I'm suggesting.
When FreeFULLOL is dead and gone the standard 810 and 215 designs will still be around and breaking backs and taking names, so don't get too caught up in concepts that have been around since the dawn of amplification. Get what is comfortable for everybody that doesn't have to move it, and is easy to find at your local GC.
I fixed that for you.

EDIT: Written/posted whilst a few previous posts appeared. All in good humor... I even have an SVT worshipping buddy I play with; we go at it much the same.