I have not heard the Cremona M's as they would not work in our LR, and I never considered the Elipsas. So for our LR 2-channel system, I ended up getting a pair of Auditor M's and extended their considerable bass response with a REL B-2. I got the Auditor M's and the REL (and a bunch of other goodies, actually) from Don Better of Don Better Audio. He believes that the Auditor M's need considerable air behind them to perform well, and they are positioned accordingly in our LR. Having heard them at varying distances from the back wall, I absolutely agree with his approach. I believe that the 2-inch clearance from your rear wall would not even begin to allow the Auditor M's to sound as good as they can. And believe me, they can sound phenomenal!
I appreciate your concerns about matching speaker timbres in a home theater system. In our home theater, I ended up mixing Aerial 10T front LR's in with Paradigm Reference for the center and rears and surprisingly enough, it works - at least for me. Regardless, I would think that staying within the Cremona line gives you at least a reasonable chance at success with mixing speaker models.
I wish I had more specific advice to offer. I hope the limited information I have provided is of some value to you.
Good luck!
4Musica44107