Walnut -- you are correct on all counts. The only thing to add is that by going to cable cards you lose two-way communication, so you can not get PPV.
Larryken -- very interesting, first time I have heard this, though I don't read AVS forum, so it may be old news. I bought the TiVo Series 3 the day it was released, that's how much I missed its UI compared to the Comcast box we got when we got our HD set. I was so happy to have TiVo back, I might have overlooked a difference in picture quality. Had it been truly noticeable, though, I think I would have noticed it immediately. Can you say more?