I have one and love it. Most of the pros and cons have been discussed already so I'll keep my comments to additions and differences...
Looking around the cockpit framing is a huge plus for me. I used to have to move the plane to keep an eye on a bandit when approaching for the merge, and merging. Clearly not an ideal situation and IR tracker lets you do this simply, intuitively, and instantaneous. It can alternatively be done with hat switched set up for head position movement, but they have very slow move rates in game.
I've never had this gunsight problem in planes. I think the key is how you set the gains up around center position. I think my shooting has improved tremendously with IR. One advantage is looking forward and to the side on high deflection shots and watching the tracers relative to a bandit 'below the nose'. In some planes that's a big improvement. But I find the best thing is the way you just follow the bandit similar to how you would in real life. The smooth continuous tracking helps me develop a better sense of speed and distance relative to my plane that I couldn't get with snap views. That helps me a lot in scissor maneuvers and close quarter crossing shots.
I have found the gunsight issues in Tanks and Whirbles when zoomed way in. Setting up a single toggle to switch back to fixed views corrects that problem as stated previously in the thread.
I highly reccommend it.
