We've had a dedicated server at Bytemark since 2009. This has always been physically located in Manchester, which has been fine. However, recently Bytemark finished their own wholly-owned data centre in York, and naturally wanted as many customers as possible to move.
I was a bit nervous about this - although our service from Bytemark has been good over the years, especially the uptime, their support team has been a bit hit-and-miss lately.
In fact, they completed our move well within the proposed migration window, the server came back up correctly, and we were able to keep the same ranges of IPv4 and IPv6 we've had for years, with only the addresses these routed via having to be changed.
There was an unfortunate follow-on cock-up a couple of days later, but at least they fixed it promptly and wrote up what happened. That, incidentally, is exactly why every managed switch I've deployed has all the unused ports set to disabled...