Bluetooth mice will experience a degradation in performance but not enough for you to notice, I would expect. The ones we have here are fine, even with 10 other BT devices operating in close proximity. Bluetooth is much more robust around interference due to adaptive frequency hopping. Now, if your microwave is in the next room, all bets are off. :P

Also, if you buy a really cheapo BT mouse, you should expect to have equivalent or worse performance than your current situation. :P The logitech DiNovo or MSFT mice should work fine, though.