I normally run a full backwards cleat position, but today I moved them 2 mm forward, nothing was changed on the bike. I immediately noticed it was easier to "get over the top of the pedalstroke" and much less constricting in the aero position, this should be because I was able to "drop the heel" more at the top of the pedalstroke. Unfortunately after 40 min of riding I had to stop and slam my cleats back again because I was getting severe hot feet and this was with the extremely stiff sole of a Bont shoe. I have had similar issues in the past but at the time I attributed them to oversized and flexible shoes. After moving the cleats back, I instantly noticed more hip closure in the aero position again, even when I was consciously trying to drop the heel.
So I would say if your interest is being fast, you should definitely at least see if you can get along with a more forward cleat position. Now I'm thinking I might need to look into adapter plates to get my cleats even furter back to see if that can completely eliminate my hot feet problems.