I did a build with MX Blacks, lubed and filmed with 100g springs. They were obnoxiously heavy with SA keycaps, unusable. When I put OEM profile Tai Hao keycaps on them, they actually felt decent though, but still a little ridiculous.
I think if I put maybe 80g springs in them, they would be enjoyable. They are very, very quiet and fairly smooth. I have to say that I miss the clack with them. They're a little *too* quiet. The reduced travel didn't bother me much, and I agree they do feel slightly "rubbery" even before lubing.