Y not mine Geist Geld ? It's GPU friendly and has 15s blocks and Escrow transactions (and might soon get other funnehs)
Meanwhile, if you want to mine a CPU-friendly cryptocurrency while mining a GPU-friendly cryptocurrency you can mine Tenebrix
Full disclosure - both are currencies I am strongly associated with and allchains.info sez that NMC is by far the most lucrative GPU currency to mine.
Are you using the escrow code from multicoin? Isn't that broken? There was a discussion on the bitcoin-dev mailing list about issues with it IIRC. What testing have you done on it?
I only followed the discourse on github, current version of multisign from most recent multicoin-exp works, tho requires nonstandard transactions to be enabled (I think I said that in the faq and in the thread...)
Testing done - making and redeeming escrows, making and redeeming in different order (key order, that is), trying to use bullshit keys (with predictable result)
A bunch of other folks tried it out without dramatic fail (though I specifically warn users that this thing is verily experimental in the "crutches" tabs dedicated to sending and redeeming escrow)
Hmmmm... you know, maybe when I finally update TBX (can't quite make up my mind about how to go about fixpile) I might release a proper GUI for GG with no nonstandards and no escrow (just for people who feel uncomfortable with nonstandards, would rather not deal with them, and just need to move their GG to the exchange, lol)