We're forgetting something very important here.
Firstly, I would say that we need the toolserver running, for at least 2 more years. My guess is, it will take most of next year, to get labs to a state where it is a viable replacement that people *want* to switch to; then the next year as people slowly move over.
However, what we should really be concerned about, is not the hardware, or how labs is different to the toolserver. It is DaB. If we screw up with hardware, labs, etc, we can start over, buy new stuff, whatever. DaB we cannot replace. And if the toolserver needs to keep running for the next year or two (which it does), then we certainly need DaB. And quite frankly, that is the real issue at heart here.