I agree that you should let your ears be the judge. And I also sincerely believe that you should sit down with the keyboard and play it, particularly after tweeking the master EQ, which makes a huge difference in the sound quality. Set the User1 EQs at 5, 3, 2, 5, 10 and then press store1.
As for whether or not it's an upgrade, I personally believe it is, but again, it all depends on what you are hoping to achieve. I've only owned one Technics, and at the time I thought it was a great keyboard, but I like the PSR-3000 a lot more, especially with its ability to do so many things on the fly.
One of the best sources of information for the PSR and Tyros series of keyboards is
www.psrtutorial.com which has an outstanding forum and fantastic resource section, incluidng detailed, well written lessons on using the keyboards.
Good Luck on your decission,
Gary
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Travlin' Easy