Definitely an inspiring story with Balsamiq, though I do also see it as competition to Dabbleboard, so -ahem- you know where my loyalties lie.
On top of all that, the product seems pretty cool.
you certainly can do it, and the perks you mentioned are spot on, but i've always found it harder to stay motivated when not around startuppy people.
Bologna is not a cheap place to live, although IIRC maybe he had some help with the apartment, which would be a big contribution. Italy in general is pretty expensive these days, especially considering the salaries.
A++ would do business with again.