I have done quite a lots of flight test with infra red. Generally, it is an excellent safety enhancement. It does have limitations though, and the pilot must be aware of them. It is possible to see through thin layers of mist or fog, but "cloud" will stop the image. Care must be used, particularly when flying at night, as you can accidentally enter cloud, while following the infra red image display.
Certainly worth the investment thought...
This is a photograph of the display, while I flew a FLIR equipped EC-120 on trials in British Columbia....
