That's why I have multiple boxes. And I get 1080p which you don't, from every single box.

The AppleTV UI sucks. Worse now with the new software than it ever was. Widely publicized that this is a UI that Steve Jobs shot down long ago, for good reason. The old ATV can only do 720p, doesn't support high bitrate video, doesn't support HD audio formats, doesn't support DTS, etc. The new version does 1080p but still has all the other limitations. But ATV also does AirPlay, including mirroring. That's its strongest feature.

Another box can play any format media and is an extender for my PVR. Another Box can play any format media and also stream from the web.

There's not a single box, with any amount of hacking, that does it all, and IMO, not much reason to try and do it all with a single box. Use the one that's best suited for the purpose. I don't use any of these boxes for music for example, since they all suck terribly at it. For that I have a Squeezebox or iOS device (other than AppleTV) to run iPeng. Including the two Squeezeboxes, but not including iPhones or iPads, I have 5 streaming devices, soon to be 6. 4 in one room, the second squeezebox and the as-yet-to-come additional product in a second room on a different floor.

I may retire SageTV in favor of WMC and a pair of XBOX 360's, but I'm going to wait until later in the year to revisit that plan.

It's cheaper and more versatile to buy a new AppleTV and a WDTV Live than it is to spend any amount of time and frustration buying ATV2, buying ATVFlash and spending time hacking it. Unless someone's making minimum wage, this much is fact, not opinion. Time is money.

But anyway, XBOX 360 is the only product that will work with Windows Media Center. And there is no other PC-based PVR platform on the market with extender support. It will also handle streaming from the network and locally attached storage with codec and container limitations - only MP4, etc..