So I'm just curious how this works. The MOX has 355MB of ROM with 2,677 waveforms while the MOXF has 741MB with 3,977 waveforms. ROM refers to how much total storage there is for the waveforms (samples). I guess I'm wondering if besides adding new bigger waveforms, were the MOX's (Motif XS) existing waveforms improved (made larger) in the MOXF (Motif XF). Do certain waveforms get re- sampled to improve sound quality? Are there waveforms that have been carried from the original MOTIF Classic unaltered ?

Partially, all of the above... The biggest significant difference between a MOX and the MOXF was not just more than double the Wave ROM, but double the number notes of polyphony, so even if Voices are using the same Waveform, in the MOXF there is likely more detail and nuance available. For example, take the Full Concert Grand, in the MOXF the Key Off Sound is implemented. Due to the 64 note polyphony of the MOX, this Element was not activated.

The XA CONTROL found in the MOXF-series puts this expressive feature under your fingers so that you can better articulate musical phrases by making available different behaviors controlled by how you touch the keys and interact with your physical controllers (buttons, pedals, etc.). The 8 Element Voice architecture, found in both, is primarily used to give the performer more ways to alter the sound during a performance. Changing how the instrument responds beyond just the two dimensional play you get with most sample playback instruments. For example, the legato articulation detects when you connect notes in a phrase and will access a different Element to sound… rather than retriggering the attack of the instrument sound, this articulation control will access a non-attack Waveform. If you attempt to do a guitar “hammer-on” with this legato you do not hear the guitar pick on each successive note - the XA CONTROL - legato - smoothly transitions to the “legato Element” which does not have the picked attack. When articulating a bowed string or woodwind instrument phrase where there is one “stroke” or one “breath” but several notes in the phrase, on a standard sample playback instrument every note is attacked, attack-attack-attack, but with XA (expanded articulation) control your phrases sound more natural as the attack only occurs on the first note in the phrase and the rest can be “woven together” without the same attack portion of the sample. And that is just one of the different uses for XA CONTROL. With the MOXF having 128 notes of polyphony, more options for XA CONTROL are revealed.

The is no written documentation of which Waves were improved or replaced, however, the MOXF has a "lookup" table so that when it encounters a MOX VOICE it chooses an appropriate substitution. The MOXF has the same Wave ROM as the Motif XF... And of course, the ability to add some 2,048 user selected Waveforms with its Flash Board expansion option! This additional memory remains accessible even after powering down and rebooting the instrument.