It does have a horizonal top tube, doesn't it? In that case, smaller is better. I like to use a seat post with some flex (Thudbuster or Specialized CG-R) (or see the bike picture at the top of the page) on that type of bike, but I can't get the seat low enough on a large frame. Food for thought. Either way, a longer seat post will give you a smoother ride.
My biggest problem with going a little large is I lock my elbows, making the handling a little twitchy. I should be able to have a slight bend in my elbows in the drops. Of course, it is easy to change a stem to make the reach a little longer or shorter (if you are close).
My inseam is 32, which gives me a 88mm seat height (from pedal center) and 64mm reach with my torso. 54mm actual top tube with 100mm stem is perfect (although sometime I still like to go 10mm shorter).
I think you'll be fine with the 53.