I too have ATV1 hacked with Boxee, however, I don't even try doing video. Pandora is the only app I use on it. I'm curious also about the Boxee box, though reviews are somewhat mixed. I doubt that B&O has the Boxeee Box in their PUC and it's hard to imagine they will any time soon. If (remote) integration is important to you (it is to me), you may want to add Lintronic to your system. It will allow you to control anything with a Beo4, though with the Beo5 you have now, you should be able to control Boxee w/o a problem.
Boxee Box will be light years better than Boxee on ATV1 I know, but I'd be interested in hearing your opinion of the Box once/if you get it.