Hi Mickey. Actually, I have a couple of MMTs. I'm selling one and keeping the one I have mounted on my old but trusty Oracle Paris. Both arms are pretty much identical in condition, operation, etc., but I'd been looking for an auxiliary counterweight that came with the MMT originally. I had to buy a whole 'nother MMT to get one!
The MMT works and sounds great with my Soundsmith-retipped Shelter 501 II. The MMT effective length is 239mm, 10mm longer than the Jelco arm. I've been keeping an eye out for info on the Jelco because I thought it would be nice to have what is, more or less, a modern version of the MMT. I'd go ahead and buy a new Jelco, but of course, the mounting distance is different and I'm not too good at making mounting plates!
-Bob