I think the U last is sleek, but not "too sleek". I mean, I could say the same for the F last then - "too clunky". The F last is timeless, yes, but the U last is just as beautiful. There are so many examples of shoes on the U last that have turned out to be stellar here. Just because the U last didn't work for you doesn't mean it won't for him.
This sounds to me like preaching a religion: "There is no god but jesus!!!!!111111".