Ted's Camera's has certainly got some of the best prices going at present
they wanted nearly $1200 for that one 4 months ago
I was tossing up between the sigma & a 70-200 F4L & went for the canon
I always wonder what the sigma would have been like, it being F2.8
It has fairly good reviews here:
http://www.photozone.de/Reviews/canon-eos
Bryan