Here I just recall a question I asked Rubbia after the talk:
"You recalled the history of the Z discovery and subsequent LEP studies in motivating a muonic Higgs factory. I would like to point out that at the LHC we have not measured a non-zero Hmumu coupling yet (nor the Hee for that matter, nor we likely ever will). Arguably the Hmumu coupling could be zero, or equal to that of electrons. So we are relying on the SM to hold in order to have a chance to see it breaking down. It is a lose-lose scenario, at least to some extent."
Rubbia's answer: "What can I say..."
Admittedly, mine was a sort of flippant comment. However, I do stand by the concept: are we really willing to invest large amounts of money and place "all our eggs in one basket" by going gung-ho for a Higgs factory, when we are not even certain that we will be producing it ? Would it not be wiser to stick with the technology we now have (proton-proton collisions, maybe at higher energy and intensity) until, at least, we do discover something that requires studies in leptonic collisions ? I fear we are running the risk of crashing into a wall otherwise...
Furthermore, although a muon collider is a wonderful concept, and it can indeed help other research fields such as neutrinos and CP violation studies, I am not so sure that the physics output we would get would pay the bills. Just my two cents, of course!