For any of you who'd decided to stop syncing from the UK2 Arch mirror (mirrors.uk2.net), the new high-spec server is now in action, and mirrors.uk2.net has been changed to resolve to the IP of the new box - 18.104.22.168.
The problem with the previous server was primarily that its discs couldn't keep up with the demand, so it was spending a lot of time in IO wait.
It has been replaced by a box with SAS drives in RAID10, 24GB of RAM for plentiful caching, and dual quad-core Xeons - so should be far more capable of handling the load.
Therefore, those of you desiring to sync from a UK mirror but who were put off by previous problems, firstly please accept my apologies, and secondly, you should find things *much* better now.
If you happen to see any issues, of course, please do let me know, but all appears to be working well.