Don,
The polyphony is the same on the Tyros and the PSR3000. Both have 128 and the Tyros does not include a hard drive. You have to buy one and add it inside. You can have a USB hard drive with the PSR3000. Although not all the styles in the Tyros are stock in the PSR3000, you can copy and paste all of the Tyros styles, or get them on the psrtutorial website and load them into the PSR3000.
I for one have sold dozens of tyros keyboards but now only sell the PSR3000. I think it is a better value.
George Kaye
Kaye's Music Scene
Reseda, California
818-881-5566