I've just tried this out, after a few tweaks here's what I've found:
Firstly, you'll find that FS needs the
TrackIR SCP DLL as mentioned in the 3.6.12 final release thread:
http://www.hard-light.net/forums/index.php?topic=70692.0In order to get it working properly, you need to select Fake TrackIR (otherwise FS won't detect the input) as the game protocol and invert the pitch.
Notable limitations: the non-commercial version of the API used limits face tracking to the first camera connected to the system, sorry capture card users.
I found that the default smoothing settings to be too strong, resulting in a high latency between moving my head and getting a response from in game. Personal preference was to move most of the sliders to near minimum values, and to turn EWMA filtering off. (whatever the hell that does)
In terms of system resource usage I could happily play BP2 with no noticeable slowdowns on an Intel Core 2 Duo @ 2.2Ghz, Nvidia GeForce 8600GT and 2GB of RAM.
CPU usage (out of the game) peaked at about 20% when open and 15% when minimised to system tray.
In terms of gameplay, it feels fantastic, using it gives an incredible feeling of immersion, even more-so when using a "show-ship" .tbm for cockpits.
Put simply, this is Freetrack without the hardware hassle.