No offense guys, but this topic is kind of like debating how many angels can dance on the head of a pin.
Given Dish's inability to do even minor bug fixes to the 721 for months and months, I think we're kidding ourselves if we think the current generation of PVRs will get new features. It appears that, while Scott does receive beta tests occasionally, the 721 program is on a barely-lit backburner, at best. If we get one additional software update, I'll count myself lucky.
I like my 721 and was giving serious thought to a 921, but Echostar has become so UNfocused since their merger with Direct TV fell through, there's no way I'll be throwing an additional $1000 their way.