I happen to straddle the fence between the two camps, filter on when outdoors (mostly), off when in the studio. I have used the Nikon Neutral Clear filters for many years on my lenses now with little to no impact on image quality. But I tend to walk about with the lens cap off.
Another fine article Mark. Epson has been releasing some very good papers in last few years, lots of choice now. I look forward to the write up on your negative digitizing setup (VHRIS), I know you have been working on it for some time now.
Thanks for sharing that interesting storyline along with those gorgeous photos. I agree that these are much more dramatic in b&w, a real joy to view. Looking forward to more of your articles.