Validity of ACES criticisms?

Until they fix shift to magenta and 8 BIT PRORES on export and incorrect colors with prores source files from alexa cameras on import, I personally doubt it.
I’m tired of instructing vfx-artists how to deal with all these bugs, so they could send me high bit depth files back without any change in colors.

It has per channel tone (highlights mostly) mapping, then primaries conversion of the tone-mapped image, then linear-to-rec709 (not gamma2.4) encoding. So, how it affects out-of-gamut colors depends on source gamut.