I failed an 84% chance desynth a dozen times in a row. I also notice that I am much more likely to get an NQ result with high HQ chance than I am to get an HQ with a a low HQ chance, but that is probably observational bias.

The big thing I notice is MCHs 50% chance for combo procs seems to be much lower than that. Being on PS4 though I don't have the parser to test it and I'm not going to do a 1k sample size using pencil and paper.