In reply to abr1966:
Been in SIDI shoes for years now, I always go up one size from street shoe size and they fit perfectly, I always swap out the stock insole for a Specialized BG insole which takes up a little bit of volume anyway.
Best way is to buy from somewhere that does free returns and order a couple of pairs, i would suggest Sigma Sports as they have a good range of SIDI, Merlin often have them in the sales too.