I have an M12. I think it sounds really nice, and is quiet. I've not used it a whole lot yet. I've never used Mackie, though I've been in a studio that used them. They are ok. I think he was using the Mackine preamps to record with, though I didn't look closely, and didn't ask.
I have some JoeMeek, and other stuff I'd much prefer to use and I put my dedicated front ends directly into the Alesis ADAT HD24, so the fact that the M12 is not an inline board is not an issue. I like to keep the signal chain simple, and couldn't see using an inline board. I got it for its reputation for great preamps and British EQ, and for the fact of its 24 bit S/PDIF out. Yes, they do say they're the same as in the Ghost. Short of using a Ghost, or Allen and Heath, or some very expensive console, I think it's one of the better boards available these days, for a compact home studio. I'm not speaking from experience of using others,,just what I read, and I can say it has a very nice sound. With 12 mono inputs and two of the Stereo channels, that gives me 16 tracks,,which is enough for me, having come from a Tascam 788. I use the other two Stereo channels(post fader) for effects returns, and use the mix inserts to run an RNC to compress the whole mix, in Real Nice Mode.
You can chain at least two of them together too, from what I understand, which is nice, when you need more tracks.
