Hey, I think I can help answer some of your questions...
I bought an M3 on Musician's Friend about a month ago. I've been using it at my band's rehearsal space along with a Sterling Audio condenser mic into the Line Input. With this setup, recording as a 16-bit, 44.1 kHz Sampling, we get some really good audio... definitely demo quality with just a single room mic. I've also used it to record my DJ sets, where I aux send into the M3 input... I usually do this on 320 kbps MP3... These come out really excellent, partially because it's just capturing audio that's already recorded, but it also has good transparency, as the recordings sounds REALLY close to their original recordings...
And for the price you can't beat this thing. I was looking around for a while and decided to give this thing a shot just based on the price. I am very happy with it. So happy that I'm thinking about picking up an HDR7 which is a similar unit from Ikey but with 24-bit and 96 kHz sampling with built-in X/Y condensers...
As for customer service, I can't really answer this because I haven't had any problems with my unit where I need to call them.