Wow! I've been off-line thanks to Hurricane Sandy; but I'm catching up. My take away so far is:
- consider low ride front racks b/c a 210 lbs. man on a 62cm bike already loads the rear wheel heavily. However the bike does feel balance for and aft when I ride it unloaded.
- longer rear racks will allow me to shift panniers rear-ward to help clear my heels but amplify the rear loading problem.

@robo, thanks for the link that is a nice collection of rack stats.