reducing glare with linear polarization

[calypsob]

tiffen offers several types of polarizer http://www.tiffen.com/tips_polarizer_filters.html
I am interested in the ultra, the plain linear, and the warm linear.

Each claim to be able to rotate and reduce glare and the warming filter claims to reduce blue shadows created by the flash. I was wondering if anyone has some photograph examples of the linear polarized warming filter because I found one that will fit my camera for cheap. If anyone has any advice I would appreciate it before I purchase a polarizer. My lens is a reversed pentax so I dont need a CPL filter but would a linear disrupt anything else within my T3i? I generally shoot in full manual mode when doing macro work and I really want to cut some more flash glare out of my shots beyond the capabilities of my diffuser. thanks

[archer1960]

Linear polarizers supposedly screw up autofocus, but since you're shooting manual that wouldn't affect you. Seems like it might be worth a try; you can't break anything.

[LordV]

You will only get significant glare reduction in strong natural sunlight not with flash.
If you are trying to reduce the glare from flash you need to also polarise the flash guns with a filter but you then start getting a lot of light loss
Brian v.