It will work, but the total capacity is significantly exceeded (33t total difference, 29t is the ideal max). A Mid Cage (GS) rear mech would be ideal with a compact . Again, the short cage (SS) will work, you will have to size the chain carefully and avoid cross chaining.
Actually i just read the specs for the 6700-ss and it said
Total capacity 33T or less
Largest sprocket 28T
Smallest sprocket 11T
Front chainwheel tooth difference 16T or less
So i think 11-28 should be fine.