Glory - I've been using a Memory Player for the past 3 years and I really like it. I bought directly from Sam, but it was in from a previous buyer who was upgrading, so not the most recent model. I really like the sound - I think it sounds better than the Aurender I used before it. I've also played around a bit with both USB (SOtM with superclock) and the Lynx AES16e AES outputs too, so its flexible.
The only real negative for me, and this may have been improved in more recent versions of the MP - the user interface isn't great. JRiver works fine, but you really need to read up on the different JRiver settings and versions, because Sam doesn't offer a true manual. Because of this, it took me a while to get it set up the way I have it now. It's definitely not a plug-and-play device like an Aurender, but again, this may have improved in more recent versions of the MP.
But from a technology standpoint, I think that Mark's IDEAS software that removes jitter artifacts that are part of the recording is pretty amazing and unique. All of the competitors' jitter-reduction techniques that I've read about are all at the clock level, but the MP is working in a different direction. This is the main reason I bought one...
Dave