I own a pair of 3100's, currently used as rears and a pair of 33s which I'm not currently using . . . now there's a clue.

The 33's are great speakers with a good crisp, precise sound. They're compact, sealed (infinite baffle) and support 24/96. On the downside they sound more thin and clinical than most M speakers, don't have a great bass response and there is no display or IR receiver so they are pigs to configure and you're never really sure what's going on. Oh, and unless you've got a proper wall-mount or stand arrangement they are unstable due to their curved sides.

To my ears the 3100's sound better in every way, particularly bass response and they are a better tonal match with other M speakers. They also have a display (which you can turn off if you prefer) and an IR receiver. The icing on the cake is the DSP processor which runs at 150 MIPS so it has enough horsepower to apodise, which the latest firmware supports. If your main source is MC200 this may not be too important to you, but it does also mean they are more likely to support any future developments M come up with e.g. the Bass Control feature currently only on 7200's (but that's speculation on my part).

The only potential downside in your case is the port. Actually it's not a downside under most circumstances - this is not a speaker which suffers from port 'chuff' but if you have a really restricted space then it might affect the sound - only a demo will really tell.

Ian's suggestion of using the 3100HC's would be a great solution in your case - unlike the vertical version this has two mid/bass drivers and is sealed. I used to have one as my centre and it was a cracking good speaker - but it's not an exact tonal match with its vertical twin. Obtaining a pair might prove a bit difficult.

As for 3200's, having heard them a few times I personally think these are not so good. I'm guessing this a sort of development of the F80 design concept i.e. using the bass driver purely for the low frequencies and a combined wide range mid / tweeter for everything else. And we're back to no display/ no IR receiver (cuts costs I guess).

DSP3100 is hugely underrated - in my view it's the best small speaker M have produced to date.

Main: 861v8+ID41, 218, HD621, DSP8000SE u, DSP7200SE u, DSP7200HCSE u, Oppo BDP103D, LG OLED557BV.
Second: 218, DSP3200, DSW.
Other Rooms: 1) F80 + MS200. 2) F80 + MS200, 3) F80 + R Pi. 4) F80 + R Pi, 5) F80 + R Pi
Vintage: 207 CD Pro, Lecson AC1 + FM1 + AP3 MkII, Quad ESL 57s