If you want the new HD channels, you do not have a choice. I switched prior to the channels rolling out. I thought the switch from Tivo might be a little hard but I have been very surprised with D's box. It has been just as reliable as the Tivo and, once I got used to it, just as easy to use. If you plan to stay with D* I would go ahead and make the call and get the ball rolling. You're missing a lot of great HD. (As far as Tivo and D* joining back up--don't hold your breath.) Check out the D* forums on www.DBSTalk.com
for a lot of info specific to the HR-20/21.
for a lot of info specific to the HR-20/21.