I find it hard to believe that any of those reasons you cite are genuine reasons that people would run production stuff on Xen. I'm sure such reasons exist, I just don't know them.
An Introduction to Full Virtualization With Xen (Linux.com)
Posted Oct 27, 2012 1:25 UTC (Sat) by ixs (subscriber, #47170)
[Link]
Xen offers considerably lower latencies for both disk IO as well as network IO.
Even with PV drivers kvm is not even playing in the same league whenever we test this.