Freepbx questions


I have few general questions concerning freepbx. i would like to get advice on how should i approach the following setup. multiple locations (10-15) office environment requires voip and possibly T.38 faxing.

would it make more sense to have a box at each wan site (max # of extensions 20 on one site, with average 5-8 per office) have mesh vpn between them ? concern is that with location with few extensions, does it even make sense to have dedicated box.

another solution is to use dedicated server colocated at datacenter and have all offices connect to it (vpn implemented as well). wouldn’t want to host it at 1 office location because of bandwidth concerns.

also i hear that virtualizing is bad idea, not so much for the calls but conference, CDR because of the timing issues. would i run into issues having xen host (dual L5420 with 8GB RAM) with one pbx vm possibly another one for site-to-site vpn trying to handle 50+ calls? just would like to know if anyone has some real life experience with virtualized setup. thanks in advance for your advice.