Don't trust any servers to anyone. When we get a new server we check its stats against reality (have had upside and downside surprises on CPUs), run bonnie++ to make sure IO is as expected (it hasn't been due to exotic RAID problems), and run memtester to see if we have bad RAM (had that too). Takes more time, sure, but no surprises later.
After <i>the conversion from Apache [+passenger] to Nginx [+unicorn] overall throughput went up by a factor of 3.</i><p>I noticed a similar gain (10-12 req/s to 25-30req/s) for action cached pages after switching out nginx+passenger for nginx+thin. This is on a 256mb slice, and seems totally counter to the general opinion that passenger is great for VPSes.