I discovered in my research that Helicon makes a Voice Live Play GTX which includes effects for guitar. This unit has a midi input. I have rented their Harmony M pedal which does midi but I found that they would lock up or suddenly not produce harmony and needed to be rebooted.
I also play guitar and the freedom I get from my Digitech reading the chords is what I'm looking for when I switch to keyboard. Last spring before buying my Yamaha PSRS 750 I had rented a PA 800. I could live with the harmony onboard even though I feel Digitech is better. I could not, however live with the $3000 price tag. Thought Yamaha's PSR S950 would be my answer but Yamaha's VH2 is drastically flawed.
PS Dave, in one of the 900 demos on YOUTUBE there is a really nice redhead. She sings well and even has a few freckles.