I'm 6' and 195lb and had same tough decision when I found the 2013 on clearance sale last summer. I Went with the 157. it was a good decision. The board is faster than any board I've ever been on, and stays above the powder better than 162 and 159 hybrid Camber boards I own.
The one thing I noticed is that the t rice does not like to have its speed checked. it can do long carves just fine, but as soon as I try to dig an edge in to reduce speed, it wants to pop off its edge. It is stable at blazing speed, becomes unstable real quick when you try to slow down from that speed. I think this is just the nature of the board, and I think the extra length in a 161.5 would make you faster but wonder if the extra length would make it easier to check the insane speed. I'd be interested in what others have to say about that.
I love my 157. It has pushed me to become a better, faster rider. Whichever size you get,just be ready to develop a new style of boarding... speed, and if you are not comfortable with that, start looking around for another board.