Replying to Armada T-hall sizing help?? +k

Ok so i decided to get this years armada t-halls because all the sites are having great deals on them... so I am gonna pick up a pair soon...

I weigh 152 and im 5'9" 1/2

i do a lot more rails then jumps so the size options are ether the 176 or the 181?

the 181 seems pretty big.. and its not rockered but i don't know how much of a difference in sizing it makes!

any input or help will be nice! +k for help