I've never used a steelpad before but the extactmat is really good.
When using it you get no resistance when moving even when using a £10 A4tech mouse which I was using (yes I heard the groan). It seemed to make the mouse a little bit more sensitive to movement.
As you've probably read each side has a different coating, so far i've only used the sensitive (flat) side and i've not managed to scratch the surface yet but I really haven't been trying.
I'm now using a Razor Diamondback on it and I have to say that's a nice mouse. Fantastic sensitivity on it, no more jerky sight movement it's smooth as ya like. Perfect for a nice head shot!