TRACK-IR works well within the limits of the graphics card to keep up, i.e. a quick glance can often leave you way off the beam by the time the graphics catch up, running the sim in lower resolutions helps some for those with mid range cards, other than that the redering limitations in the sims leave a lot to be desired at times with distictive veiws of runways often not becoming visible untill five or six miles out and less for unlit grass strips.
I found that locating a distinctive 'Always visible' feature helped you home in on the target during visual's as for Instrument approaches, you gotta trust the machine is all and resist the temptation to look outside at all untill the last few feet, worked every time once I got the idea.