I had the 8400F at home and was pleased with it, so I bought the 8600F for work when I needed to scan in a bunch of graphics. For this job, I found it to be a really fast scanner. Both the preview and the final scan of the color graphics were speedy. Sorry, but I did not use the scanner to scan negatives, so I cannot comment on that.
You can tell more about a company when something goes wrong than when everything goes right. The scanner I received had problems with streaking during the scans. I called Canon and got right through to tech support. They spoke English (meaning, it didn't sound like an overseas call center) and determined after 20 mintues that the scanner was bad. Two days later I received a brand new replacement that worked great. I highly recommend buying the Canon brand based on this experience.
I have no regrets buying this scanner, but here are a few things that Canon could do to improve it:
1) The USB cable was a tad short (about 4.5 foot). A 6-foot cable would have been better.
2) The top of the "scan area" is by the hinge of the lid. That means you have to open the lid wide to put something in. For areas where you are limited in vertical space, it would be better if this were moved to the front of the scanner.
3) The scanner cuts off just a hair along the edge of the item being scanned. The edges are how you keep an item "squared" on the scanner, yet 1mm or less along the edge was not included in the scan.
The software that comes with the CanoScan is good, especially Adobe Photoshop Elements 4.0, which is always rated well in the PC magazines. The CanoScan driver is flexible with plenty of options for the advanced user, as well as basic options for the not-so-advanced user.
I expected a good quality scanner, and was surprised at the speed. I recommend the CanoScan 8600F to you.