I reviewed its less expensive 'rival' for Avsim not so long ago - REAL SKY PRO EDITION FSX version. It was a review combined with the FS9 version too. I compared it to Flight Environment (although not the FSX version, as it was still just about to be released). Even so, you might find the comparison interesting, not personally tried the FSX version of FE though. Link to my review:
http://www.avsim.com/pages/0907/Real...RealSkyPro.htm

Chock