It all depends on where you are and what kind of riding you do. 180 is a LOT of board; at one point I rolled the Lib Doughboy 193 but it was more of a novelty. I've just stepped down from the 172 to the 165 and am happy with the smaller board (me: 6'3", 225#). You'll get a ton of float out of the 172 with out all that extra weight/length of the 180.
At 6'3", 225 pounds and size 12 feet there aren't a whole lot of boards out there that will work for me. I've been riding Lib for years but finally decided it was time to step down from my Skunk Ape C2 BTX 172 and get onto something a little more 'playful'. First day out I was throwing f/s and b/s 3's off of every little hit, something I hadn't tried in a long time. I'm so stoked I made the move to a shorter board, I only wish I had done it a few years ago. With the C2 BTX I get the float I need for pow with the camber for groomer power. Throw in some Magna-Traction and you're ready to slay whatever the mountain throws at you.
It should; I bought an XL and it was too big for me (6'3", 220#, 34" waist). It seems to run big in the waist and for me was hanging off my body