My passion for 1980's home keys is well-documented, and I have found the Holy Grail.. The Yamaha PSR-36 has the sliders to edit the FM synth engine, much like the mini-keyed PSS 360, 460, 470, 570, 380 etc. but with mad features: 4-operator FM (instead of 2), which can be detuned against itself (!!), 61 full-sized keys, a extra-long sustain and improved MIDI.
Here, I am demo-ing one of mine with a Behringer digital multi-effects pedal. I am going to install an analog delay mod.. Keep an eye out! :)