Scott,
Obviously, the third voice will not be available because the 3000 is limited to 2 voices for the right hand. As for getting another 2000, the 3000 offers so many advantages when it comes to storage, it would be difficult for me to play a 2000 after using the 3000 for just a few months. So many wonderful things that can be done on the fly using the USB and Smart Media Card in conjunction with laptop. For anyone set up in this manner it provides the ability to perform seamlessly with zero dead time between songs. And, while some folks will argue that the difference in sample size between the Tyros and 3000 can be heard, your audiences will never know, or for that matter, hear the difference. Even after all these years, I have a great deal of difficulty hearing a distinct difference, especially in the voices that are freqently used such as grand piano, guitars, sax, trumpet, etc. And, in your case, where the Tyros is your primary machine, the 3000 would be an excellent back-up should the Tyros unexpectedly drop dead.
Good luck,
Gary