The 3500 (whenever it comes out, probably next year) will not add that much to the 3000 (besides a higher price ;-) ), so I wouldn't wait if I were in the market for a 3000.
Like Springs said though, the RFX6500 provides much better RF performance than the 6000 if you wanted to keep your TSU7000.
Mike
www.SurfRemoteControl.com