Hi
For the most part I think if the pitch is not exagerated it does not affect you very much, but if the pitch is severe it can really affect you. I have a 16 ga o/u francotte that had severe pitch and when patterning the gun it caused the gun to shoot very high for me. I trimmed the stock to be more neutral pitch (about .75")and it lowered the poi many inches I think about 8"-10"(at 16 yds). That is my experience.
Jeff G.