Replying to Surface LL2s (rockered)

i'm thinking about a pair of these for this next season but i cant figure out what size to get. I am 5'7" and used to ride a 179 hellbent, and I dont know how exactly the 179 LL2s measure up to those, because i know all ski brands measure a little differently than one another. (for example I put one of my hellbents up next to one of tim Ds bentchetlers last season ans his 183s were a lil shorter than my 179s)
also i heard these LL2s are alot lighter than bents or ep pros, thus meaning i can handle a 189, but i dont want to make a mistake and get to big of skis, so i need your opinion, im 5'7 and 135lbs. and if they are as fun as everyone says they are, I will be skiing them pretty much as a one ski quiver, mounted dead center.