Blender Underground

I came across this page:
http://www.blendernation.com/2012/01/16/using-sharp-edges-in-blender/#comments
This guy says edge split is the way to go when getting sharp edges on a subsurfed shape.

Personally I have always used the Sharpen Edges method (select edges, then key Shift- E, 1) since it worked for me and didn't need another modifier.

So what is the diff? Why use Edge split instead ?

Edge split physically splits of geometry, but it's only suitable for non-subsurfaced models. It's used heavily for realtime models to control smoothing.
Edge sharpen on the other hand, controls how smooth the sub-surfacing occurs between to hard angles.

Thanks Ronnie. I have seen it on imported models and so on and wondered what use it was since it makes more verts. I always thought that gaming engines wanted less, but there you go. All a matter of where you are sending your model .

That's not entirely correct since vertices aren't rendered and don't tax your GPU pipeline at all. It's the polies that are a drag. Using edge split on separates a face from another, it doesn't create any new faces.