It appears that the coolr things you can toss in or turn on in your TiVo are natively in the ReplayTV. Plus, they seem to have paid the patent royalties for the tv "grid" instead of the modified but royalty free format TiVo has.

On the other hand, as you note, the hackability makes the TiVo rather interesting to me, for many of the same reasons the empeg is.

And:
The interesting thing about the Tivo is that it takes the unused space and will record things that it thinks you may like.

I saw a comparsion of TiVo and ReplayTV where they were snarky and pointed out "we don't guess what you like, instead you pick from categories of stuff you like". Where, I presume, they put stuff in the categories, meaning they guess what I think those categories mean. 6. half dozen.

The Moxi might be interesting enough to convince me to get one, but I already have a TiVo with lifetime (the $200 plus the $100 I paid for the thing, combined with having it for almost a year, means the Replay almost certainly couldn't compete on price anyway, since it's too late), and my TiVo won't be hand-me-downed to my parents, since I also already got them one, also with lifetime ($129, theirs is a 30hr, mine is a 20, upgraded to 100-something)

I think it depends what you want. If you want to play at all a series 1 TiVo is the right choice. (Find one used). The Replay has some more interesting features as shipped. The other thing is since you need to decide what you like, try to play with both, find friends that have them.

I'm not sad I went with the TiVo, or that I have a pile of spares to play with. I am sad that I don't have time to "hack" a TiVo and start doing mpeg extraction, or time to do anything with the extracted video. If someone put something free in my lap I might change my mind but I have to go with the TiVo as my recommendation.

I don't expect anything free, or to be willing to spend any money until something like a Moxi hits the market, either, actually.