ribbed grips on upside down

A friend of mine has recently purchsed a set of MP32's with the grips on upside down. Obviousy the pro way round is the done thing nowerdays for round grips but these grips are actually ribbed.

Apparantly Langer started this some time ago as it positions the grip correctly on the club and also enables players to get increased compression on the ball. This is rumoured to be where grips the pro way round may have eminated from, but I think Tiger started that one.

Does anyone know anymore about this? Can anyone think of any draw backs with this?

After hitting a few balls with the grips like this I am serioulsy considering doing this with my irons

I hadn't heard of it before but apparantly it's more common than you would think, Greg Norman used to do this and so do many of the blatest tour players.

I know players like Hogan used to poistion the ribs on his grips open but the benefits from this are obvious, the benefits from the ribs being upside down are a little more difficult for me to desipher.

You would apparantly get similer affects from using a putter grip on an iron, this is banned under R&A rules so it must have some benefit I'm just not sure exactly what.