I migrated my Linode from Xen to KVM yesterday; I had a ticket open and needed to migrate my VM to a different host anyway, so I decided to simply migrate to KVM.
After shutting down my VM and clicking "migrate", the migration actually failed, which was a bit terrifying for a few minutes. I was definitely worried that my disk image went poof and that I'd have to restore from a recent backup. Thankfully, Linode's support was there to kick whatever failed and the migration worked after all.
My VM feels a bit more responsive on interactive session, though I haven't benchmarked anything. (I don't really need to, I only serve a few low-traffic static web sites.)
