However, regarding remote setups, is X forwarding significantly superior to using something like VNC? I've never done a side-by-side myself, but most of what I've read indicates that VNC is usually faster.
As a semi-experiment, a few months ago I decided to try running Firefox in a Linux VM, and render it in XQuartz on my Mac host. The experience was not pleasant, to say the least. And that's what I'd think to be the best-case-scenario for latency. Hard for me to imagine using it over WAN.