All of my personal partners have been well endowed, but in the hobby it's difficult to navigate. Simply because it's not a constant so there's no warming up to it. I always do the best I can and am very open when it is not comfortable for me and we change to one that is better for the both of us.
If I'm relaxed, I can take most anything in stride. But if you have someone viciously ramming you like a virgin during his first time, even average can be uncomfortable.