Replying to Rocker advice. +K

I am looking at getting my first pair of skis with any rocker at all. I need a new all mountain and i really like the durability if the on3p Jeronimo so Im pretty set on getting those. My question is should i get 171 or 176. Im 5'7 and about 135. I have 171s right now and i like the length but wouldnt go any longer. With the rocker in these should i step up to a 176? They will be center mounts. any help or even suggestions of other all mountain mid fat rockered skis would be fantastic thanks guys.