Larry, This is exactly my predicament. I have a PSR 3000 in excellent condition. Is there really a justification to spend even $800 in the S670? It is certainly tempting.
If your happy with your sound and features on the keyboard you have keep it and enjoy playing it,....if you want or need everything the Psr3000 doesn't give you vs the newer keyboard on the market
then buy a NEW model. The decision is
YOUR & YOURS alone
for
YOUR needs it's as simple as that.
The justification is in
YOUR Head only.
Good luck.