for me its not so much a question of questioning his decision to buy a canon - i agree a
second hand 1Dmk3 would be a serious alternative to a 7D but rather questioning why he is moving away from Nikon just because 'he's tried them and didnt get on with it'
imo if he didnt get on with a nikon dslr theres a good chance of spending 1400 notes on a canon then finding he doesnt get on with that either
instead i'd tend to suggest looking at why he didnt get on with the D80 - if its just a case of wanting better low light performance etc then he'd be better off sticking with nikon and getting a d300s or a d7000
if its a case of it being big and heavy then he'd be better off loking at something smaller like a G series or one of the evils
and if its just a case of thinking a new camera will make him take better photographs then my advice would be to save the money and just practice with the D80 until hes taking the best pictures its capable of.