I believe I may have read the blog before. Looking at his graphs, it appears he is doing the unmap *before* the Compellent takes any Replays(snapshots), i.e. moves his Active data to Read-only replay. The Unmap command will work I am sure if done before the Compellent moves his Active pages to a Replay. If he were to do his test after a replay was taken, I am quite sure it would not work.
So bottom line to me, it is impossible to use the unmap on a Compellent system unless run continuously or something. Unless someone knows another way. I may try again and see if zeroing out the Active pages, can someone translate into zeroing his corresponding blocks in the read-only replay the next day.