bose-x: Blimey, nearly 10,000hrs on my polarised Maiu Jims so far. I had no idea I have been doing it wrong for so long....
Polarised lenses can be an issue with some windscreens as some screens, due to their construction, (usually on commercial aircraft) have a polarising effect and the other issue is some cockpit displays also polarise the light that is transmitted. Couple these with a polarised lense and then you have a potential problem.
No doubt you've seen the effect of placing one polarised lense over another and rotating them.
Photochromic lenses need direct sunlight to darken. They are not very effective when sitting out of direct sunlight (like you normally are in a cockpit) looking out into bright sunny skies.