I have the latest OS and have used the Kemper for the past 5 years. The transpose feature has always been one of my biggest disappointments in the FX department. It sounds almost synthesized and 'phony'. The latency still is unacceptable for live performances to me.
I get that it's not perfect, but I've never heard another transpose effect that has zero latency. If you've got some clips or a recommendation where you can't even tell it's doing it regardless of what's being played I'd be surprised and delighted. It's like being angry at physics.