Hey there. I came accross this post looking for some info on the VidaBox, and I thought I'd respond not because I know a lot about these products, but mostly because I hate when nobody answers my posts. I've researched the multi-room functionality of AVR's, and I'm always unsatisfied when I begin to imagine what it would be like to control the sources from the second and third zones. Unless I had a graphical display, RF capable remote, I'd go nuts trying to control it with a regular remote with no line of sight, or walking back and forth between zones.
Info on the VidaBox has proved hard to find, but a web interface offers a lot of possibilities for control/access from other zones with a laptop or web enabled phone, even. You'd still need to power your speakers, but a decent one should only be $400 or so if it's not required to process your video signals.
Seeing as how you posted 2 months ago, have you learned any more about these solutions? Made a decision yet? I'm very intrigued by the VidaBox.