Matt - first off I think you will like the systems, especially if you like minimal heel/toe lift and increase response and support. I know I wouldnt trade mine for anything.
But I just wanted to confirm what Stephan said. the 2012 system boots as a whole used a different last (mold) to create the boots, and as a result the boots came out a little smaller than most shoe sizes. For example, I wear a 10 by most shoe mfg's and for my 2012 murrays I grabbed an 11.
However, for 2013 there was a different last used to make the boots, and as a result the 2013 boots will fit very similar to most shoe sizes. This year I grabbed a size 10 pair of Process boots, and I couldnt be more excited to get out and ride them.
With all that said, if you want to heat mold your boots, its possible for that extra 1/2 size to be packed out or filled in from the heat molding process, depending how much room is in your boots. The molding process wont change the size of the boots significantly, but if your toes are cramped up front, it will expand a little so they are more comfortable. Or if there's some extra room in the toe box, the foam will puff out and fill in some of the dead-space. Again with what Stephan said there is some personal preference involved.
To simplify things:
2012's - go for size 10s
2013's - try them on if you can. If not, and you like a tight boot, get 9s. If you like some extra flex or "wiggle room" then go for the 10s.
Hope this helps, and hope you dig your new systems.