I think as long as you are healthy and in decent shape your "friend" should still be performing at 23. It might slow down a bit, which is fine, but it should not be a problem.
I also think you should take into account if it is sport f*ckin' or love makin'. That might affect your performance/friend's reaction time.
And as for numbness, I had a saddle that was terrible and causing me to wake up in the middle of the night with shooting pains in my nether regions. I even saw a doctor. Switched saddles and the pain went away within a week.