This is part of the reason why I ended up moving to a larger frame:
http://www.bikeforums.net/showthread.php?t=344648

On the smaller bike, I had to have my seat ALL the way back just to get the plumb line thing right. Now, with the longer frame, I feel better with the centered seat, and it's even easier for me to get forward over the crank when I want.

Re Treefox's sig: thank goodness my bike's red.. lol