Not the M32/X32, but our band replaced our XR18 with an MR18, build quality wasn't massively different but the preamps were noticeable better. We were able to pull config out of the XR18 and upload the MR18, and swap them directly. Everyone in the group (all in ears, axe-fx only, electronic drums) noticed an improvement in the quality of mixes. It was a straight A/B, we did a few songs on MR, then swapped out to XR and redid same. We didn't do a blind test or anything though, so maybe everybody just believed it sounded better.