Aurora is nice. I had no idea about the Volpe not coming with braze ons for a front rack this year. That's a pretty poor choice for Bianchi, I'd say. You could get another fork, maybe the one they use on the LHT, but it's nice to be able to get a bike that has everything you want to start with. The nice thing about all your choices is that they are quite versatile--especially with the Volpe and Aurora you can slap some skinny tires and do some road rides, or thicker ones and do moderate trail riding, and though I haven't ridden the 520, the Aurora and Volpe would be great commuters (in Portland Volpes and their single speed cousins are becoming quite ubiquitous).