Kirkus. Btw, I never imagine you own B&O,I'm a huge fan of Bang & Olufsen, and own piles of the stuff . . . actually I own a B&O store. I just don't discuss their current product on Audiogon because I like to participate as an individual as opposed to a business, and want to avoid a conflict of interest. It's also a very misunderstood company in the specialty-audio community . . .
But anyway, the I've mounted MMC20CLs in other tonearms, and been very impressed (usually SME IIIs). I also used to use a TD124, and had two armboards with salvaged B&O tonearms - one from a Beogram 3000 where I used the SP12, and another from a Beogram 3400 where I used the MMC20CL. I also used the SMEIII on the TD124 with the MMC20CL. But I've never really tried them on medium- or high-mass tonearms . . .
I generally feel that my current Beogram 4004 is the best, most balanced setup for this cartridge, and it has by far the best tracking performance. On the 124, I always felt the bass was better, and there was a bit more impact and dynamics, but it seemed to give at least as much away in terms of clarity and detail.