Advertisements Time to upgrade!!! I have been comparing the two HD DVRs, and trying to find the justification in the price of the Series 3. Now that I can get a "Factory-Renewed" Tivo HD DVR for $199, there is a $400 jump to the series 3. The only differences that I can find are the remote (means nothing to me), the storage space (I will expand whatever I get so that doesn't really matter), and the THX certification of the series 3. This is where I am confused. They both have HDMI and Optical outs. What are the actual differences in the internal hardware/software that make it THX certified and is it really worth $400?