Photocromatic sunglasses

In another thread, some folks mention flying with these "light
sensitive" glasses.

I have a pair, but find I must use clip-ons while driving, as the
glasses apparently react to UV, and the car's windows filter most of
it. I have also found that same effect, though a bit milder in the
sailplane. In my onwn plane I wear sunglasses that fit over my RX
ones. Just got a pair of Bolle (Vigilante) glasses that accept a
prescription insert, and have interchangeable lenses, but they fit
reasonably well over my current glasses, so the insert will be a new
year's present to myself.

When hanging around the airport and taking an occasional hop in the
club 2-seater, I just use my regular glasses, and in both the L-23 and
ASK-21 my glasses lighten up to a very light shade of gray. Both
gliders have non-tinted canopies.

My glasses have no tint at all indoors, and turn a very comfortable
gray (almost too dark if outside temp is below freezing) when out in
the sun. But in the cockpit, they tend to lighten up enough to be
annoying for anything more than a hour or so of continuous flying.

So... what experience do others have with these types of lenses?

-Tom