Thanks guys, maybe it's enough to convince him, although I'm reluctant to take responsibility. I think he said he has a Grace unipivot, it should be good enough for great results.
Quite an impressive list of carts replaced by ART9. You have me drooling. I just purchased a TT81/7045 and I want to get that functional so I'll will have to wait for a bit. It's at the top of my list.
I can understand how a 100Hz cu of 18 can be scary. We developed a 10Hz conversion based on AT MMs. It works to a limited extent, but not in all cases. The problem is 100Hz cu is not really a measure of compliance. It's more a measure of cu + tracking ability at 100Hz. Compliance at 100Hz doesn't make much sense.
Regards,