I've seen more hard drive than PSU dying in datacenter move, which is usually solved with having a few spares and good backups, obviously external from the datacenter being moved. But same can be said of PSUs. Obviously the more heterogeneous your servers are, the hardest it is to have spares for everything. Everytime we did some DC moves, we used that opportunity to replace a few old servers which meant we bought a few spares. The big question is if the Xen project has the financial capacity to buy a handful of servers.
Let's keep in mind we are talking about a relatively easy move. This might be inconvenient for the DEVs but this is an infrastructure (CI) that is not customer facing and that can survive being offline 2 or 3 days. Users can still download the deliverables, developers can still code in the meantime.
This assumes the Xen project keeps half decent, fairly up to date documentation. I could see them not founding admin work as much as they should.