To be honest, with the 40mm f2.8 and the Canon EF 70-300 F4-5.6 the only "loss" in term of equipment would be the 10-18, that is pretty new right now and i can sell it to obtain with a little extra money the Samyiang 14mm f2.8, that is really good (only manual but, at 14mm is ok)!
I'm thinking about it and i'm also looking around for some good offer, but i also love to shoot and if i didn't found a really good offer for the 5dMkII i'll probably go with 60D (the 1.6x factor makes the 70-300 very long)
Thank you for your opinion