I can't seem to find it, but I thought I remember seeing a post here indicating that Comcast is gonna switch their encoding of ALL channels to mpeg4 (or maybe another format) and therefore this will make ALL Series 3s obsolete (except local channels).
I have 3 Premieres and a Mini, but I also just sold a Series 3 on ebay and one on Craigslist. I then also have one more S3 (OLED) unit. This unit works great and its still one of my favorite TiVos (with its look, front clock/controls and recording status), but I may have to sell it as well if this is the case. Just wondering.
I also am aware of the power supply issues with these units and I have already had some caps replaced on this S3 OLED unit so I should be good for a while, but if Comcast is planning to make it obsolete, I guess I may have no choice here.