The PM1000 has great N3v3-ish sounding preamps, but lacks in output level as standalones. This may not impact WWforum low level recordists, as you can get very solid sounds at the levels they advise.
The EQ is a very primitive three band semi-para of the 73 type... totally non-surgical and not very musical.
I don't think the PM1k has direct outputs or channel inserts.
The mix bus sounds like mush when hit (not in a good way, in a smeary way).
There is no real routing compared to even a Blaringer or Make-me mixer. No true stereo inputs or outputs.
You can track with a PM1000, but racked up channels are actually better IMHO than the whole board since the pres and the XFMRs are the only really cool attributes.
I would not mix on a PM1000 unless I had to.
The PM2000 has great sounding preamps of the API school.
When in proper order, they sound excellent.
The EQ is a crude version of the 550A type, but lacks the vari-Q which makes the API significantly more useful and musical.
The mix buss and routing are usable, but not ideal since busses and masters aren't calibrated stereo faders but assignable mono faders.
I have mixed on a PM2000 and been happily surprised with the results. I also own one and have a great affection for it.
The m1516 and m1532 are very close in most respects to the PM2000 but have switchable redundant inputs for other applications (theater?, television?) and a slightly different EQ, metering and matrix.
I also own one of these that I track with regularly.
All three boards are XFMR balanced at every input, insert and output. I think all of them also share a weird design flaw, unbuffered meters. You can only switch them in to look at them, then switch them out. They adversely impact the sound in a way that I don't dig.
I consider all three to be among the best buys in pro audio.