The later Yamaha models Tyros. 2100. CVP's do hold onto the present voice until you play a new note. But the bug is it does change the Effect setting immediately from the new voice.
Example:: Piano is being played. Select next voice Strings. The Piano still plays whilst note is held but with Effects from the Strings which is bad.
My 9000Pro works as it should do. The effects for the next selected voice only changes when the voice changes.

Graham.