Asalaam alaikum

  The reason to do or not to do an action should be based on the how Allah and His Messenger (saaw) rule on the matter. Sexual activity is one of the most critical actions that a man undertakes. The believer seeks the guidance of Allah and His Messenger (saaw) in this matter, not that of scientists or doctors.

  As for the medical effects of masturbation, I cannot agree with the list provided.  There are certain realities of masturbation which are damaging to the person, including causing abrasions, tissue damage, even flaccidity (unable to get erection) etc. 

  Ultimately, the Muslim man must consider that Allah (SWT) is watching him  and the angels are recording his actions.  

  May Allah (SWT) grant us taqwaa to do the right thing and avoid the wrong thing so that He (SWT) will be pleased with us.

Usama