I would suggest to test it for a couple more days. I was annoyed by the hiss as well in the beginning, and now I’m using high for take off and mid for cruise, i might be wrong, but i believe ANR can only dampen lower frequencies which leaves the higher ones being only passively dampened, due to the cut off point on the frequency range we notice the higher frequencies more now that the lower ones are mainly removed. Yes, the ANR switching, i believe it is the tap to talk feature, happened to me as well on landing. I switched to the smaller tips which gave a better fit in my ear, better noise reduction and no ANR switching anymore as the fit was better and the earbuds didn’t move as much. The cord is basically the same as on the A20, in both cases i clip it to my outside epaulette which removes the pull on the headset itself.
Still not entirely convinced myself though, but currently i lean toward seling the A20 off, not the proflight.