I've recently come to the conclusion that coffee does affect my flacid by about 1/4 to 1/2 inch or so but there are just so many other variables within my body that affect this as well. Some people aren't affected as much or at all. But in the morning after some coffee my little midget seems to constrict for a few hours until after noon. I just have one cup of coffee in the morning and maybe 2-3 cups green tea throughout afternoon and night. Effects from green tea are hardly noticable, just maybe slight constriction.
I will be doing the same soon with the coffee. That stuff gives me a lot of anxiety and sometimes minor panic attacks and now that you've said it makes you impotent I think I want to drop the coffee altogether for now. But I'll keep drinking my green tea.