as a synth player I’d appreciate a good frequency shifter. I’ve several in software and suprisingly the one I liked best was the one Arturia had in the Moog Modular – most of the rest aren’t so good. Analogue units I think are very expensive and most of the modular ones I came accross were a bit more expensive, were digital and sometimes problematic. So a decent frequency shifter on an H9 would be very nice.
