Originally Posted by BluesDawg

Shimano says you'll need the new FD, so that's the official answer. Real world answer will have to wait until someone tries the new crank with their existing FD. If there is enough adjustment available on your outer limit screw to move the derailleur out 2.5mm, I can't think of any reason it wouldn't work just fine.

For all of us running SRAM shifters made for Yaw type FDs, thus having no trim steps in the shift pattern, I sure hope it will work.