Mike my 2cents - I have no practical experience but have read several reviews recently In anticipation of buying a lens myself.
The L series are in a league of their own and a bit more than I really want to spend also I get the feeling that the 17-85 is not all it could be.
This site has a good range of detailed (and independant?) rewiews of various lenses on the EOS range. The Verdict at the end of the report on the 17-85 is worth a read. Interestingly they also rate the Sigma 17-80 a better lens.
http://www.photozone.de/8Reviews/index.html
Go the 17-40L, you know you want to.