Ed,
I have the PSR3000 which in the area of data storage, I would think, works very similar to the Tyros.
When I use the USB, all that happens on the 3000 is another tab becomes active and I have been able to move from tab to tab, copy/cut/paste, even while a song is playing without a hitch.
My money says that it would be OK, BUT/FYI, I don't have much money.
[This message has been edited by MrEd (edited 03-30-2006).]