Wayne, I read your article on switching to SageTV from Media Center; I have wanted to get away from Media Center for a little while now. I've tried out MediaPortal because it was free and offered the similar server/client setup that SageTV has but I just couldn't get comfortable with the user interface and its instability. What keeps me with Media Center really is the interface and the ease of configuration. I find that more important than the lack of features and open-ness compared to SageTV.
I realize that the SageTV extenders work better for "extending" than the Xbox 360 but I would have a 360 (or 2) regardless because I love the gaming experience and all the other features it provides especially knowing whats coming down the pipe in the next year.
If MS would implement Media Center into WHS to allow for a server/client structure I would jump all over it. Or, if SageTV were to somehow compete with Media Center on its interface and ease of use then I may consider switching. Also, having to install a 3rd party application isn't as appealing as the built-in Media Center experience. Right now I just move all recordings to my WHS once they are done and with the new power pack with WHS it makes these recordings easily available to all other PCs and extenders.