I just got passed the 72 hour manufacturer break in period recommendation on both sets, so I'll be sharing my final results soon. But even after a day, I felt the FX2s were a big step up. This is probably because they're a better match for my larger speaker set up. The FXs are barely able to keep up with my Def Tech SR9080s, so that would be a sideways or even downgrade if I keep them. I do think they would be fine with the Motion 40s and below, both in size and soundstage.
Build quality on both are fine, but not as nice as the towers or centers. Neither have the gloss black, but instead a matte black finish. I don't like the non removable metal grill on the FXs, but don't care for the fabric grill on the FX2s either, but they do look very cool without the grills on as they are removable.
Huge differences in size though. The FX2s are flanked with really massive tweeters.
More details to come...any questions, ask away.