Hi Guys from Australia
50 something owner of an IT business specializing in EDI.
About 7 years ago moved from 12 physical machines to VM's
Been through nearly all of them
now have a 64 core, 32 core and 32 core machines running 23 VM's
Currently using XEN however I find it a bit flucky so I do a bit of "forced reboot" via my automated system which fixes the problem.
Only program in XOJO (basically visual basic) so not sure if I will be any help as a developer here but if I can help testing of any of your systems or you need a spare server please ask.

thanks
Damon