Assuming the results are permanent and can not be changed, I rather be smaller and last longer.
Why? Because with a 8.5 quick draw, you are first adding discomfort, then dissapointment. By the time the pussy adapts to the size, its over. You would be a lousy lover with a useless dick.
5.5" is not a small dick. It is average and unless you have a size queen, you should do OK when you focus on how to use it.
I think most women would prefer the same.