Hi JT
My advice, in the absence of being near a music store, would be to check out as many YouTube presentations as you can
Also, download and take a look at the Yamaha PSR-SX 600 700 and 900 User Manuals and Reference Manuals.
That will at least give you a pretty good idea of what each keyboard will, or will not do, to suit your own needs.
If possible see if somebody near to you possibly owns one of the above, and would let you play it?
I spent a great deal of time doing this before settling on the PSR-SX700 which I am extremely pleased with.
Keith.