I used the hat switch for years.
I got Track IR a couple of months ago. It's so much smaller, and so much more.. precise.. .than I had imagined!
I too played with free track, but never could quite get it to work right. I think the old Logitech webcam I was trying to use just couldn't get the focus right. Never could get it to work reliably.
Last week, I was heating up some leftovers while my plane was climbing out, and I heard a check six call. I come back to the computer, and sat down real quick and got into a 1v1 except I hadn't put on my trackir gear. I was trying to keep SA using the hat switch, and I had gotten so used to the Track IR in such a little time, I just couldn't keep track of anything without it. I ended up winning the fight, but only because he was a poor shot.
I too had to turn off the 'roll' axis... well I didn't turn it off completely... just moved it all the way down. This way I still get maybe 5 degrees of movement.. just enough to make it seem 'realistic' but not enough to screw with me.
If you have no problems flying around looking at different directions (looking forward maybe only 20% of the time), then you'll LOVE Track-IR... but if you're the type that has to look forward almost all the time to keep track of what your plane is doing, you might not like it so much.