I will say that I also notice some very slight nuances in the actual tone itself. When he was playing single note arps, it did sound like a guitar, but more a guitar where the action was either a bit too low, or what we guitarist dread (a warped neck)--which in turns causes what's called "fret buzzing". To me I hear fret buzzing in the sample. It's possible Roland added that to try and make the sound more authentic.

I've heard some samples of bass guitar that will also add fret buzz to the sound itself. Whether this was intended by Roland I really can't say.

As far as the strumming in concerned, I think Roland did a great job there

Squeak