+10 on the Sidi's... I wear a pair of 47 (Euro) megas. (Normally wear 13 4E)

Sidi's are more pliable so they will conform to your feet better.

I personally did not like Shimano shoes because they were extra stiff on the upper sole making it rather uncomfortable inside of them.

You can find cheap pairs of Sidi Carbon 5.5 Mega's on ebay. That's where I got mine. $250 retail for $170 shipped.