I ordered the thicker F-Pro mount.
The seller stated that the thicker glass in F-Pro version provide a stronger polarizer effect due to larger reduction of light transmission. Is that correct? Never heard about it before.
It's mostly the filter ring that is normal or slimmer, not necessarily the glass that is thicker or thinner. The thicker ring is more resistant to deformation. The Käsemann versions are better edge sealed and supposedly use higher quality optical materials (glass and foil), and are re-polished for plan-parallel surfaces after cementing/mounting the foil.
Here is a decent overview of the various aspects involving Polarizers. The
B+W filters handbook from Schneider Kreuznach Optics also has such info in their Polarizers section.
Cheers,
Bart