I have both Roland GK and Casio PG-380 setups, but neither is exactly state of the art, though both are useable. Last week when I wanted a quick synth part I used Jamorigin MIDI Guitarist to drive a Sampletank patch. It's surprisingly responsive and requires no special hardware aside from a relatively low latency computer. I've been curious about Jamstik but haven't played one.

DC Ron
BiaB Audiophile
Presonus Studio One
StudioCat DAW dual screen
Presonus Faderport 16
Too many guitars (is that a thing?)