Anyone here have experience with DIY head trackers?

[Synthesis]

What latency? It has a direct USB connection to the system.

With regards to other games, yes, it works and works well.
It is seen as an analog joystick by your system.

[Sokonomi]

Normally when theres a processing program involved it may induce a minute bit of latency, but if it straight up installs as a joystick its gonna be pretty lag free.

[grumbleweed]

Bit late to the party, but yes, I have the 9150 which I built myself just using the edTracker PCB and self sourced bits from ebay, probably about 25euro all in.

Its really great, I have no experience with any other headtrackers, and I can't say I notice any latency, although they do mention it as a downside. I dont thin kI could play without it now to be honest. I actually have a spare 6050 which was also good, but suffered from heat related drift, which isn't a big problem until you don't have that problem any more!

Just make sure you calibrate it EXACTLY as they tell you to on the site, there's a good video of it here:
https://www.youtube.com/watch?v=J2xCjdC4X0I