How good is the paravirtualized clock?

I need to provide good time to our network infrastructure, and users and am wondering if it makes sense to have RHEV VMs as stratum-2 NTP-servers, connected to various stratum-1 NTP appliances. Will virtual machines keep good enough time to be used as NTP clocks for other servers? 

I've noticed on serverfault.com they're quite negative to running NTP-servers on VMs: 

http://serverfault.com/questions/106501/what-are-the-limits-of-running-ntp-servers-in-virtual-machines?lq=1

is there any truth to this, or just old wisdom from the horrible vmware days? How good will the timekeeping be? Within 30-100ms as suggested on serverfault, or are there reasons to expect the KVM paravirtualized clock to perform as well as a physical clock?

Will VM migration be problematic for NTP? Maybe best to not migrate these VMs?

KVM timekeeping reference document:  http://lxr.linux.no/#linux+v3.8/Documentation/virtual/kvm/timekeeping.txt

Original kvmclock documentation: https://lkml.org/lkml/2010/4/15/355