I currently use the Emotiva XPR-1 monoblock amplifiers for my front three channels. If I had to look at upgrading, I would be going after the Parasound JC1 monoblocks for left/center/right. Maybe a Parasound A21 for the surround channels.
Since you are ultimately wanting to get Martin Logon electrostatic speakers, I would probably look at a higher power amplifier. The MC303 is a good "future" choice if you are after that sonic signature. The Parasound JC1 would be different. I think it would have a lot more detail and slam and punch when compared to the MC303. I'm sure the MC303 will sound beautiful though. It might still be a better match to a Krell Foundation and the Martin Logans.