Sorry for the late reply. Actually I've been running leased bare metal servers for most of the time. In the last couple years I've had some clients and projects on linode and digital ocean, but still have bare metal servers for most other stuff.

I haven't knowingly used virtuozzo for anything so I can't say. Most VPS I've had have been xen-based, but the hardware behind it seems to make more of a difference. I've got two virtualized xen projects right now, and same code on seemingly same virtualized hardware specs still yield pretty different results on some tests.