cPFence I decided to add a separate swap partition for one of the servers, and left the swap img for the other so I could compare. I always prefer separate partitions. Another deviation was I upgraded the ubuntu installer at the start so I installed v24 straight off the bat. No issues, or messing with post dist upgrades.
slimx I didn't see this article of yours, interesting technique. I'll bare that in mind for other purposes in future. It was actually the tip off for Alpha that made me take the plunge, I'd previously done my own setup exactly like this guide (cPFence) but on oneprovider over a year ago and they sucked! perf was terrible.
One final caveat I will add, don't go and select all your sites and try moving them all at one go. I ended up in IO hell and things taking days due to this... after everything finally failed, doing a couple at a time vastly improved throughput and got it all moved within a few hours. I was quite surprised at the io on the hetzner cloud volume, that was the major bottle neck when trying to read too many snapshots at once.