That would work, unless you're using a container-based VPS. OpenVZ is notorious for standing in the way of system tuning. Using nginx makes a lot of sense in this case, especially with the ey-balancer patch.
> SO_SNDBUF: [...] The default value is set by the wmem_default sysctl and the maximum allowed value is set by the wmem_max sysctl.
You can't use sysctl under OpenVZ. QED.