I've had the LPA-1 for a few months powering my Axiom M80 speakers, and I really like it. Absolutely worth it and it'll be a part of my home theater for years to come.
I recently bought an LMC-1 to try out. I returned it after only a few days due to the buggy software and lack of features compared to my AVR. I'm sticking with my old and trusty Pioneer Elite VSX-43TX receiver as a pre-amp for the time being.
The sound quality from the LMC-1 was fantastic, and I will miss it. It brought a lovely sense of spaciousness, sparkle, and depth to my music, especially with SACD's. Someone else commented on an increased sense of 'attack' and 'decay', and I definitely concur with that. Very, very realistic presentation of the material.
But dealing with the "stuck" and "random" sound modes between digital PCM, Dolby Digital 2.0, and Dolby Digital 5.1, it was just too irritating. Our 'system' is used for all of our TV viewing, and so I it is important to us that the receiver/preamp/decoder work properly and reliably with different sources.
Half the time I would have to stop or pause the source, go into the menu setup, select the mode, and then resume the source. I know it it doesn't sound like much, but it became annoying every time I filpped from DD2.0 to DD5.1 to PCM channels. Also, it wouldn't/couldn't remember to stay on DPLIIx modes for PCM, and would frequently and randomly revert to DPLIIx:Music or Bypass. I also didn't like the fact that it could only apply DTS Neo processing to DTS sources. I often prefer DTS Neo to DPLII decoding for 2 channel dolby digital sources, and the LMC-1 just can't do this.
I also had problems with inconsistent calibration levels, too-high background hiss levels from digital sources, a consistent 'snap' from the mains on system shutdown, and a very loud and irritating half-second of 'SCSHHHH' noise that sometimes occured with switching to a DD5.1 source.
If you don't watch much TV that involves digital audio sources, or are mainly concerned with music, then the LMC-1's quirks will be much more tolerable or even non-existent for you.
I will eagerly await the LMC-1 "RevB" model with fixed software, or for the "LMC-2".