Upload & Sell: Off
It is the best deal out there to go to full frame currently. The 5D II is a great camera, I own now two of them, and the IQ is just great. Minor drawback is the crippled AF system, but depending on your interests in style of taking photos it might be not a big concern. I think a lot of people were and are currently upgrading from APS-C to full frame by getting a 5D II.
I shoot outdoor portraiture, landscapes, and still life.
I was planning on keeping my 40D, but now I'm considering offloading that and picking up an original 5D as a second body.