Hi everyone! I've played with MOTIF XF's internal waveforms enough now that I can list some of the issues I've experienced with the samples so far. These are subtle but some of them like the issue with Viola is very annoying.
1- Piano (I guess it's the default piano voice and not S6): in the highest keys there is one key which is a bit off tune (I can find it if it matters).
2- Classical Guitar: In the maximum velocity, in the mid notes, there is one sample has a bit delay, which means whoever created it forgot to remove the silence at the beginning.
3- Viola: One sample creates a humming effect which is used for 2 or 3 keys and they all have this characteristic.
4- Organs: I don't remember exactly which drawbar sample but there is some noise in the lowest and highest samples.
If it matters I can name the notes and sample names in detail.