So far a little bit vague about polyphony. Hope that there's at least 128 voices for common sounds like piano. It won't be the first time when Yamaha turns a keyboard into a toy by reducing the polyphony quite ruthlessly (for example, MM6).
But 76-keys version is a change. It used to be only 61 or 88 for a MM, MX, MOX and MOXF.
I think the 28-voice polyphony for AWM2 is a typo, it has to be 128, otherwise it would just be a niche product focused on FM-X.