I have a bit of the same dilemma. I am moving to FF from the 7D. I bought the EFS 10-22 a year ago and very rarely used it. But wide angle photography is something that I think I could get into. For now, I am focusing on the rest of my FF kit, but, I have been watching and a couple forum members seem to be taking excellent photos woth the Samyang 14 mm f/2.8.

A few from Ben Taylor:
http://www.flickr.com/photos/ben_tay...in/photostream
http://www.flickr.com/photos/ben_tay...in/photostream
http://www.flickr.com/photos/ben_tay...n/photostream/

While I will get other lenses first, I am debating between this (~$450) and the 17-40 f/4 for my FF wide angle option.