Isn't that why you have a pow stick? Who cares how well The Greats floats for you?
I'd jump on that deal. A 158 wouldn't float noticeably better than a 156. In fact, I doubt there would be a noticeable difference at all between the two to be honest. There's way too much obsession over small differences of size out there in the snowboarding world. It's 2cm, that's less than 1 inch. If it's a screaming deal, buy it. If you don't, direct me to it and I will.
"People say that marijuana smoking is going to get in the way of my career. I say to them that on the contrary, my fighting career is getting in the way of my marijuana smoking." -Nick Diaz