Two questions on polarizers, specifically on diferences between -brands- of polarizer filters:

1.  Do all polarizers have the same reduction in light, or do some brands of polarizers admit more light at a given 'degree of polarization' than others?

2.  What other differences (besides sharpness) are there across brands of polarizers?

The reason I ask is that I lost my filter pack, and must replace all of my filters.  There's a big difference in price from cheap to expensive polarizers, so I'm trying to establish the associated value...

Thanks in advance!

    dave