I'm using Astaro 7.5x on xen5.5 (yes, without paravirtualization, 7.9 also doen't have this... hoping for v8).
Performance is really ok, stability very good.
Only strange thing was, I experienced some strange NIC behaviour. Two nics of same type (onoard on Asus WS Board) and additional Intel Nic in PCI.
After adding Intel NIC, Intel NIc became eth1... but it should have been eth2.
Didn't have time to investigate on this... removed the Interface ;-)