I found my comparison Krome piano versus M3 XP again and just uploaded it:
https://soundcloud.com/rorosetree/piano-comparison-korg-krome-vs-korg-m3-xp-2013

The 128 MB M3 piano (the second one) even sounds better than the 2,8 GB Krome piano here, due to the sustain pedal, which wasn't connected to the Krome in the store where I recorded it. But otherwise, both pianos sound nearly identical.