Does anyone have any experience using a Polarizer & Warming Filter combination (i.e. Moose's Warm Polarizer) on Velvia RVP50? I will mostly use this combination on shaded landscape/scenery and was wondering if there are any odd color shifts if I used this kind of filter on an already saturated film like Velvia. Am I better off buying the two filters separately and stack them or is the combined polarizer/warming filter just as good?

I normally do 4x5 B&W landscapes but want to get back into color landscapes. I'm also not sure if the combination polarizer/warming filter have any odd effects on B&W film - so I may consider buying them separately if it does. My main landscape lens is an Super Angulon f/5.6 with an 82mm thread. I already have the Cokin Z filter holder but I am debating whether to get the screw in type or the square glass filter inserts.

I would also appreciate any filter recommendations if you have one.

Thanks in advance,