Ideally you need to be able to compare geometry specs including fork rake and trail. Twitchiness is an abstract concept, but often refers to quick steering. I am thinking that both of these bikes have pretty much racing oriented geometry based on bottom bracket drop, head and seat angles. So probably twitch about the same. That said, many would say a fine lugged Serotta CSI is one of the nicest steel bikes ever made and would put to shame a simple tigged Bianchi...at least for aesthetics. Ride characteristics are in the butt of the beholder. Neither of the bikes here would be considered offering a relaxed ride. A Rivendell off the rack regardless of model is built with geo to offer a relaxed ride.