Although, I am not blessed in that department, I can say, that I have been with a number of "Hung and Massive Hung" and with Average endowed men, and what i have noticed is that, the "Average" men tend to get a stronger erection, and are able to maintain it, where as the Hung or Massive hung, had a hard time maintaining a good strong erection for penetration, which can be VERY, frustrating as most of the time during sex is spent gettig "him" back up for a good penetration, which usually fails midway through..
For this reason. i tend to go for guys that are average, than, hung like a doney, because I don't like spending my time getting him erect, for it to get floppy shortly after, I have however noticed that lots of American males, even at a young age, have some form of ED problems, whereas, other nationalities that I have been with, tend not to have that issue...
Just my two cents...