Is anyone in vinyl land familiar with ADC tonearms

Yeah, they built three, the ALT and the LMF 1&2 or 2&3, I can't quite remember without looking it up. Sold for 200 or so, the ALT being under 200, And actually thought they were some of the better values in arms at the time. You would hope they mated well with ADC cartridges, Sonus and the like and they did. Unless you just feel they need for spending a bunch of money and not getting a ton of improvement, I would stay with the status quo

I would think it would mate well with anything from the Grado line

May I suggest you just try it and not ask anyone here. I don't mean that as a wise ass remark, its just that if I have it sitting here in front of me, and I think it might work, I usually try it. Your not going to hurt anything, and I personally happen to think it will work fine, but after that treatise that Sean wrote up there, I would defer to him. George Merrill is a good source though, and if you talk to him, tell him Pancho from 20+ years ago say hello. He is good audio.