But I am not sure about the website. It seems like the RRP is less than what they normally sell for. Is it legit?
IMO they're fairly true to size. I'm 6'0 and 185lbs (ish) and a size 50 in both a blazer/pants fit very well on me. I'm usually a 40R (american size) in a jacket and 34 waist. I find if I go up to a 52 it's a bit large and baggy on me.
Barena fits me fantastically for some reason -- or maybe they're just so well designed they always look good. On their sweet henley t-shirts (the nalin shirts from last spring/summer) I can wear small, medium or large depending on how baggy/slim a look I want and they all look great.
What piece are you looking at?
Have a link to the blazer you're looking at? I think the torceo blazers fit more slim, while some of the other blazers not so much. Without any other information, I'd go with your usual size.