Both the Yamaha and the Roland have a terrific split bass - the Technics & the Korg don't ... if that's a factor. As for the Steve Gadd vs. Ringo Starr comment - Sure, for a jazz situation, Steve is the better man, but I speak from the experience of a guy in the trenches who plays the hits. Any singer/pianist I know would rather have good solid timekeeper than a drummer that solo's too much, or plays too busy.(Gaddism) Take jazz out of the mix anyway - because we're talking about machines here. Mechanical, NONfeeling, NONimprovising, inanimate silicon & plastic monsters. None of which exist in the realm of jazz.
I love to add a jazzy flavor to my shows, but let's face it - you CAN'T play jazz with a machine... because it won't play back. If you take away the spontinaety and interaction .... you get pop. Maybe it swings, and maybe it doesn't - but if there's a drum machine or arranger playing ... it ain't jazz.

(oh boy ... here it comes.....)