I'm a bit late with this, but here is a follow-up to some of the Tivo install issues I ran into in November/December of 2008. (See: Second Tivo HD -- Install Issues Part 2)
I had to switch my original Tivo-HD to two S-Cards, as we had done in our secondary Tivo-HD. Since I switched to the two S-Cards, everything has worked fine on both boxes.
Also, I've tried out the Netflix via Tivo, and it looks good. I've watched two hour long episodes of Dr. Who and two 30 minutes tv shows so far. The stream and picture quality has been great.