I am really a bad person to ask if penis size matters. As a straight man I have no interest in comparing the size of my equipment with the size of others. I am quite happy with what I got. But I never had sex so I have no idea if my penis is good. I think women/gays would do better job answering this topic. Still I think that sometimes size doesn't matter. Look at this painting of mine:
In it I tried to recreate Zodd(a monster from Berserk manga). In this painting you can't see his cock. Who knows it may be huge or it may be tiny. But no one would question it. Because he is a men slaughtering monster- one man army...Likewise I don't think that anyone would tell a big bodybuilder, godfather of mafia or some influential politician that their cock is too small. Why? Because those people could fuck up your life sideways even without a real cock...
Weird medicine?
At the moment I would not agree to be a test subject for some cure. If you need a test subject use it on politicians and billionaires. If they will die at least a their wealth could make a difference for some dog shelter or other charity. I on the other hand would prefer to keep my life, my body, my mind and my cock. I have no desire to become some ugly creature with three eyes, a tail and horns...Like this:
I believe that some test subjects are paid well for what is done for them. Still I think that I would be better off without this ,,magical cure'' and its risky side effects. Just imagine how horrible it would be if as a side effect of the cure you would go blind, or become paralysed. Or lost all your memories...possibilities are endless. And each seems worse than the other. So thanks but no thanks.