Scott,
Another thing to keep in mind is that jazz guitar is amped, through an amp that has effects, reverb, echo, delay, EQ, etc. And, the song was likely recorded with a digital recorder and edited using recording software features to enhance the sound quality. All of this has a bearing on the final product. The same is true with the sounds that are produced by your keyboard, especially guitar sounds.
If you recall, there is a PSR-Tutorial member named Julio who using a PSR-2000 could produce some of the best guitar music anyone has ever heard. And, when he provided some of his earlier midi files there were folks that questioned whether he was using a midi guitar and not the keyboard. His playing techniques, especially while emulating the guitar sounds, are the best I've ever heard.
While there are some keyboard voices that probably will never sound exactly like the true instrument, some of those voices can be edited to where they sound better. It's all a matter of personal preference.
Cheers,
Gary
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Travlin' Easy