Common Projects F/W 11-12 - Page 67
Unless you have very wide feet and that is usually a problem for you, you should not worry about the width issue and just stick to the size one down rule.
The only time this didn't work was when I bought the cap toe lows last season, those were painfully narrow. For achilles, desert boots, and bball highs, 1 size down has worked fine for me.
The navy ones I really like with the black and white accents.
Mr. P has D&G achilles low on sale for 200 right now, if anyone is currently looking for a cheaper alternative. May drop more too since it doesn't have silly gold letters printed on the side for people to drool over.