I have a 2010 and a 2012 to compare, so not quite the comparison you're looking for, but it's a start. Between these 2 I see and feel a couple differences. First, the new model is thicker. The lock side liner thickness has been increased, and I believe the scale thickness has been increased just slightly. The overall thickness of the newer model isn't that much greater than my older model, but I can feel the difference. Second, the new model scales have more grip to them.
I've read that Emerson stopped using titanium for both liners at some point, I think it was 2006 or 2007, but I don't know for sure. If you buy a 2013 model, the lock side liner will be titanium and the other liner will be stainless steel. Additionally, Emerson has started using standoffs on some models in lieu of the back spacer. I'm not sure if this change has been made to the 7 or not, but I would bet it's coming.