i looked at it years ago but decided against investing in it, your post made me look to see what the stock has done since then but appears not too have done much. It seems to always trade at a discount to NAV as i recall the same bull arguments back then. Also not sure anything in particular pops out to me as showing good management, capital allocation and growth. Ultimately that's what you are buying, is managements ability to allocate capital effectively.
Essentially I was on the fence back then but what convinced me not to invest was when i saw Elkann take a helicopter to his Shareholder meeting. I always worry that family run and controlled companies could be used as a piggy bank and that behavior is ripe in Italy.