I can testify from experience that even the LCD displays on stock standard 15-year old radios become invisible to read with polarized glasses.
As the aircraft I usually fly don't have glass cockpits or other highly critical displays in them which require non-polarized sunglasses, I'm keeping them for now and just do the head-tilt whenever I need to switch frequencies. But otherwise they would be the first to be replaced. And next time I'm going for non-polarized.
bit interested to understand the issue with windscreen's since they are perspex etc
I *think* (but am not sure) that polarization can appear in any transparent material that's being stretched in one direction. Probably because that stretching causes the long carbo-hydrate molecules to align themselves with the direction of the stretch. If you have a bubble canopy then that's usually formed by heating a flat piece of perspex and then using a vacuum to suck it into a mold. This leads to local stretching and thus polarization. So it might be a problem on any windscreen that's being bent in two dimensions, but not in anything that's flat or only bent in one dimension. (Depending on the fabrication process in any case.)
(Then again, I'm not a chemist so I may be entirely wrong.)