Tigris was neutered at about 6 months. He came up with this iFLUTD (idiopathic Feline Lower Urinary Tract Disease) at the age of 9 years and he has been fine since. I cannot imagine that there is a connection.
Filou was about 9 months ( it was later when he started singing his coming-of-age songs in the staircase) and he has no peeing problems.
I must say Pichu's problems do sound to me similar to Tigris. If he is fine until next year and if he wants to emigrate to Germany we'll be happy to have him checked by our vet. I think I would want a second opinion.
When Tigris takes a bath you can see his little penis and it looks quite ok