We haven't done continued follow up throughout the lifes of all cats. We have since I've been here had a couple of people who have come back to us for cats after the cats they took of us when we first started early neutering have died. In both instances these cats were 15+ years old and had died from problems associated with old age. I do realise this is not comprehensive at all, we have only been keeping easily accessable records of cats and adopters since 2009, in the future I hope to have more comprehensive follow up on the long term health of neutered kittens. Although we always encourage feedback from new owners and have had no reports of problems that could be associated with early neutering.
By poor males I assume you are referring to possible increase in urinary tract infection? To quote The Cat Group's report on early neutering "Uretheral diameter worries unfounded - studies show similar diameter to post-puberty neutering." http://www.thecatgroup.org.uk/
It is this and FAB advice that we have used to inform our practices.
I have also (hopefully) attached the cat groups pdf on cat neutering.
We are very concerned about welfare it is a first prority always, if we thought we were causing harm we would change our policy. I have not heard of liver shunt associated with early neutering and therefore I am interested in your experiences of it.
I also agree that education is of high inportance and we wish we had more financal and time resources to get the message of responsible pet ownership to the wider public.