Hi,
I love my TrackIR 4. I use the TrackClip, I don't find the Track Clip Pro makes much of a difference.
I've seen info of how to make a cap with reflective strips with half a table tennis ball on the top of the hat (for greater field of view). I'm wondering why natural point hasn't pre-made something like this already? I'm sure lots of people would buy it.
I find the trackclip pro a bit inconvenient with the extra wires coming off the headphones. My own has already broken due to the cord getting caught up with my chair. Its also a bit fiddly getting the clip onto the headphones.