Can we put this myth to bed? Italian stage-race geo is described in detail in the CONI manual, and that geometry is largely unchanged on today's Italian bikes. The long and low thing is bollocks. For example, a 56 cm Colnago should run a 9.5-10 cm stem based solely on frame proportionality (body morphology can dictate otherwise, of course). You can also see how this works just by looking at a bike: look at where the end of the bar (curve) ends up in relation to the front hub -- with a proportional stem, it will sit right over the hub.
Just as an aside, I run a 52s with a 100mm stem right now.
I would say it works really well but there is a proviso. As a combination it feels rock solid but the front centre on a C59 is considerably longer than on many modern alternatives from the likes of Cannondale, Specialized, Cervelo and others.
This will simply mean enhanced stability for many, and indeed this is what I find for the majority of riding. Attacking hairpins however, on a long alpine descent for instance, one is aware of a tendency to understeer when holding your normal descending position. Just my experience but the longer front centre requires a shift in body weight towards the front wheel when cornering sharply and this can be counterintuitive.
I suspect that a 50s with a 110mm stem would solve the issue when descending but I do wonder how much of the stability one might lose when climbing or riding low on the hoods.
Overall though, the experience of riding a C59 makes me aware of the failings that have been in all of my other bikes to date, regardless of numerous professional fits.