If I have a 156cm board, is it prudent to...
If I have a 156cm board, is it prudent to buy a 166cm bag, or can I get away with the exact same length?
Get the larger bag, if for no other reason than you can cram some of your softgoods & maybe your boots in there, too. I ride a 163 in a 165 dakine bag, and I wish I had more room for the rest of my gear.
you can get away with the same length if you want... the 156 bag will fit up to about a 158 board...
However, David is right... Its always good to have a lil' extra room for all you goodies!