Update on this. I've bought my Brera and really couldn't be happier, SV or not. 12 months old but looks brand new, inside and out.
I discussed the roof with the dealer and the workshop. They said it could be done but would be expensive. It requires a new roof lining, the blind, motors, control console at the front and centre of the roof to control the blind, storage fitting for the rear of the roof for the blind to retract into...and the list goes on. While everything can be ordered, they couldn't give me a price then and there. They also said that even if I wanted to pay for all those parts, the man hours involved would make this a very expensive conversion.
Thing is, I actually quite like being cocooned in my car without the roof so guess I'm not that bothered after all!
I finally have my Brera and she's beautiful