It really all depends. I know tablets are now pretty much as powerful (Motorola XOOM), with dual core processors. Now the thing is all tablets would not be connected to each other, unless you go the route trip is talking about, but that sounds complicated.
I am not even going to try to keep my multi zone system on. Its set to hibernate. I did this because i dont feel that everyone will be using it right away. They will be more focused on the main system and by the time they switch over, the system will be fully booted. Now the main system I would love to have on 24/7 via sleep. Problem is, its a monster! How I did get around this is add a second battery to the mix. If you buy a good deep cell then it should be able to run via hybrid sleep. If the power get to low then it simply hibernates.