what site?
btcsportsbet.com? or
mtgox.com (the main exchange) - both seem up to me.
Here's the thing...Nothing offshore is safe if you are American. The recent poker shutdowns, Feds setting up fake payment processors, etc have proven this. The weak link is moving money. Bitcoin solves that problem in a decentralized way that cannot be shut down and if used properly cannot be tracked backed to any individual.
Another advantage is you don't need to keep a big balance at a book due to funding hassles. I send in bitcoins when i see a game/line I like, and withdraw after the game. I don't have to deal with a CS rep and a fake W_U name and stress the spelling, or any other processor. It's automated.
Yes, it helps if you are technically inclined as it's not very user friendly yet.