In reply to valjean:
Well, my own experience partly contradicts yours, just goes to show... the OP should try before he buys....
I have recently owned Futuras, Miuras, Katanas and Miura VS and find the breadth of fit pretty similar on all of them. They all have different shapes / degrees of aggression / flexibility to suit differing rock types / styles of climbing but they are all pretty comfortable on my broad feet.
The Miura VSs and Futuras are both aggressive and keep their down-turned shape (due to the P3 platform) - best suited for limestone sport and bouldering. The Katanas velcros are the most relaxed - good for grit and all-day use. The Miura lace-ups start off aggressive and precise but rapidly soften and relax - initially good for sport and slate, but after a few months only really good for trad / grit and all-day wear.
Size-wise, my street shoe is 46 (UK11). I take 43 for a tight fit in all La Sportivas, apart from slippers such as Futuras which I take in a 42.5.