Ironically I canceled my 722k order and ordered a TivoHD, so I'm actually going in the opposite direction.
I sat down and looked at the costs again, and buying the Tivo instead of the 722k gets me 5 tuners (2 OTA on Tivo + 722 OTA + 722 2SAT), and I get some additional functionality of the box. I like that I can use Tivo to stream Netflix content, and that Tivo lets you pull video off the box. (vs Dish's completely closed DVR) I already converted all of my DVDs to .m2ts files to stream to my PS3, so I figure using Tivo I can make my own archive of HD TV shows.