You'll have to try it for yourself and see. That's the advice I got and I think it is good advice. Depends on the type of photography, your personal preferences, and the type of film (ie how much exposure latitude).

It really seems to depend on the person, and the application. I've never used the 58, but I have a 72 XL and I prefer it with the center filter, so for me that means the 58 XL would definitely need one. Falloff is likely very pronounced on that lens, especially when shifted or if using front tilt. But other people might be ok without one.