I can be one to tell you I LOVE LOVE LOVE



my 80-200 2.8 "Magic Drainpipe." Never owned the 70-200 f4 but they are both L lenses and one has IS the other doesn't. One is a little newer but both are still out of warranty and still can be sent to canon for repairs.
I love the creamy bokeh that mine has given me, both with my 20D and now so far with the few shots I have taken with my 50D.
Not sure what you would be using it for, I use mine for a whole lot of Concerts and Sports and Portraits.
Don't think you are wrong in either lens but just giving you MHO on the subject matter.
Stephen Gibson