Thanks for the help! I'll have to do some tests on my camera to see what the red filter will show normally. With most b&w film I tend to overexpose about a stop anyways (a professor I once had gave the suggestion and it does seem to help, especially on tmax 100), so I'll have to keep all those factors in consideration. I always forget about the reciprocity factor too, which could be an issue if i'm dealing with 8 stops worth of difference in exposure.
I'm going to be using my 17-35mm lens and a 28-135mm lens. On film I'll most likely use mostly 24-28mm, kind of a standard landscape focal length for 35mm. My 3 stop ND filter is a slim filter so hopefully that'll cut down on vignetting a little. Oh well, I suppose I don't mine a little bit of it.
I'll also be shooting with a Hasselblad 80mm lens with a Bayonet 50-62 adapter, and then a 62-77mm step-up ring (heh, yea...I really don't feel like buying more filters than I have to). I'm thinking this setup most likely won't give too much in the way of vignetting but I can't be sure.