It's been a little more than 6 months since I switched to Sage TV. And while it hasn't always been easy (to be fair, mostly problems with my HD PVR) when I look 7MC I don't see much that would bring me back. Don't get me wrong, there are some really cool new features (Turbo Scroll) in 7MC, and the UI changes are very nice; but for me functionality is the most important thing. When I look at Sage, I see a product that embraces the way that I want to consume content when I'm home, and when I'm not (DRM). I see flexibility to use the product as I see fit, with options instead of restrictions.
When I look at 7MC, there are some great additions (some of them should have been there from the start <cough>video bookmarking</cough>), but there still isn't parity (only going to get worse as 7MC ages). Media Center is still a product where the features and direction are set by policy and politics that I don't (and shouldn't have to) understand. The most glaring is if I want more than one point of consumption I need to chose between extenders that don't extend everything, or PCs that don't deliver a connected experience.