Hiplain, FYI costa's plastic lenses are cr-39, not poly. The p is for plastic. At least in the non prescription versions, not sure what they use in rx. They make poly lenses too, but they brand them Native, not Costa. Kind of like how Smith brands it's straight poly Cloudveil.
Mj makes like 5 lens materials these days, and brands them all MJ, but there's still the big price differential. Glass, poly, and 3 different proprietary trivex clones.
I don't have experience with the smiths. But I've had MJ's and costas and, aside from clarity and chromatic aberration, the polarization on glass is superior to any of the plastics. The reason isn't the filter, but rather bi-refringence. The stress in the plastic changes the polarization angle of the light before it gets to the filter. And stress is variable throughout a plastic lens, leading to variable cancellation of horizontally polarized light. Injection molding helps, but the only way to get rid of it in plastic is to have the polarization on the outside, and no quality company does that for obvious reasons. But tempered glass in a stiff frame does the trick. For fishing purposes, I'll except no less than glass. Sports are a different matter, as impact protection gains importance.
A test for that is wear a pair of polarized glasses. Cheapos are fine. Hold the 2nd pair, the ones to be tested, at arms length in front of a computer screen and turn them. All polarized pairs go dark, obviously. But does it do so evenly? All glass lenses I ever had do. All plastic, good or bad, are blotchy.
Smith, Costa, and MJ all three do the fancy light cancelling trick at certain wavelengths. Smith calls it chromapop. Costa 580. MJ "polarized plus2" or something. It works, but I wouldn't say it's super important to me. Saturates colors more, especially green and red, without altering other colors to do it (can be done in a gray lens). Contrast is improved a little.
