Hi guys,
I experienced the same problem with other keyboards. (e.g. Yammy PSR's, KN's, X1 and SD1) I guess it is caused by too many prgchange commands or just too slow processors and ABSOLUTELY not implemented on purpose.

The SD1's delays are hardly noticeable and to be honest : I do not notice it anymore.

The SD1 has another (unwanted) feature :
After changing to another voice-group and voice, only the very first tones are too loud.

BUT : OS Version 2.0 is on the corner !

Roel