I was just hooked up today for HD with the HR21. I have read the manual but have not found anything about switching from one tuner to the other while maintaining information in the buffers. My old R10 (which I still have) has the ability (via the "Info" button) of checking to see what channel the other turner is on and going to that channel. In this situation, I can rewind from the other tuner. Does the HR21 have this ability?