In a way my PCs are just the same as a module in a rack. I don't even open the VI GUI on any of them, so I don't see any advantage in a dedicated, hardware rackmount instrument. Sure, setting up could theoretically be easier, and certainly quicker, but there would have to be very easy ways to update the instruments, add a multitude of expansion packs and stream both MIDI and audio over a Network for it to be even in the same league as my setup.
The Receptor (doesn't work with Vienna VI) is supposed to be a kind of rackmount sample player, but the specs are so out of the dinosaur age that it is not worth considering, except maybe for live work.
MIR seems to be designed as a standalone hardware unit and already there are people whining about what OS it is based on. Imagine if that was the case for the Cube as well. A few very unhappy customers I think.
DG