My 47mm Anulon experience is not with an XL model, but the one mounted in my Veriwide. It covers the 2 1/4 x 3 1/2 (6mmx10mm) format well, with slight fall off at the corners occasionally. I really doubt it would cover 4x5 at infinity, but would cover for macro work.
I use a Polaroid MP4 shutter and lens set (17,35,50,75,105,135mm) on a Deardorff 8x10 in 8x10, 5x7, and 4x5 formats for macro and they work quite well. They are made by Tominon in Japan. Much less expensive than the Zeiss Luminars, but I only contact the 8x10 and 5x7, so I'm really not gonna see much difference.