I'm owning a PS3-Eye + Trackhat-Clip (the 40€ variant) and havn't used it in SC yet, because of the known reasons. I'm using it mainly in Arma 3 for flying.
The On-Foot experience can be "tricky" to hold your head still enough when aiming, shooting, throwing grenades, running while yelling orders at people.
Camera:
The PS3-eye only delivers 60 FPS. While the TrackIR Cam can deliver 120 FPS.
There is one thing i have noticed with the PS3 Camera that when the wall is very bright (sunshine) tracking is not possible anymore.
TrackIR has a own cpu to reduce cpu load on the computer. Especially for Arma this little greedy cpu hungry bitch, you might notice a slight decrease in FPS.
Mounting the camera on my monitor didn't work well. Its very curvy on the backside. And probably i'm going to 3d print a better one.
Trackhat Clip:
I mounted it on the left side of my headphones with zipties (two have been in the box), No Problem with cables etc. Becaues i don't tend to run around with my headphones. As mentioned before tracking with bright background can become impossible. I'm not sure how well TrackIR performs.
Software:
Setting up is pretty easy, adjusting curves takes some time. On Foot i use only a headturn of about 90° (which is usally enough).
I've noticed when tabbing in and out from the game to the software, turning it on and off, sometimes results in a crash of the software and my system (windows 10)
conclusion:
If you're still unsure if you will like headtracking or don't want to spend a lot of money get the trackhat.
If you think you will heavily use it, don't buy another aurora and get the Track IR.
(I can post some more pictures later if wanted)
Another reddit regarding that topic:
https://www.reddit.com/r/hoggit/comments/3tkdjb/trackir_5_worth_the_money_or_are_alternatives/