I still stand by Maranello's. They'll outsource the mech work to a either the dealer or their preferred vendor, so the mech work actually isn't done by them but it is still warrantied. I experienced this during Q1 of this year when some guy in a jeep sideswiped me.
As for them being difficult after the work is done, I did not experience that either. The work was done, and I still had issues with alignment and such. I brought it back to Maranello's and the took care of it for me right away, and this was month or so after the repairs. Quality wise, I've not had any issues with the paint thus far.