TMY2 has sufficient detail that you don't need a 100 speed film for image quality. I don't shoot 5x7, but I like having the TMY2 option in 4x5/8x10. TMX has or had a UV blocking layer in it, making it less of a choice than TMY2 for alt-process. When I'm shooting soft focus outdoors, I like a slower film like fomapan 100 as the shutters aren't that fast and I'm shooting wide open. When I'm shooting with the symmar-s, I am using a smaller aperture and/or flash and the speedier film is nice.