I'd opt for the recommended 52mm. Its a half a degree over a rather long lever- and the Bianchi would have probably benefited from a slightly longer rake.

In small frames there are some balances between body position, front center, trail etc. That half a degree, all other things being equal, amounts to about 3mm of trail. Personal tastes dictate quite a bit, but if the people who designed the frame recommend a 52mm rake that is probably a good starting point.