I am afraid that the issue of legal operation is going to prove to be an insurmountable issue. But let's put that aside.

Don't you think a 1% fee is unnecessarily high? Why pass this out to GPU users? What are they doing for you and your customers again? Do they have any particular function that I'm missing?

Why not a logarithmic fee? Say (1/a)*ln (1+ax) where x is the amount spent and a is a constant? Then you start off at a 100% fee for infinitesimal amounts, the fee increases with x, but the proportion goes to 0% as the amount increases. How fast you converge to 0% is determined by a.  If you want you could use (1/a)*ln(1+a(x-k)) instead. Then k could be thought of as a minimum txn size, and the fee would be 100% for txns exactly equal to k.

Ideally, the system could supplant Mt. Gox and allow for a decentralized currency exchange. However, this won't work very well if you are putting in big unnecessary fees everywhere.