Replying to Magnus 102 Length?

I know just what youre thinking, "Hooray another ON3P question thread!" but hey these skis don't come cheap so I wanna get it right.

Im torn between the 176 and 181 length for the Magnus 102. I'm 5'9" (maybe 5'10' on a good day) and around 145 lbs. I ski on the east coast mostly on piste with a fair amount of narrow trails and tight glades. I currently ride ARV 96s in 177 and 2016 Line Sir Francis Bacon in 178. Both skis feel pretty decent length wise for what I do but I'm wondering if the famed ON3P rocker should play into my decision. I did the instant message on their website and they said based on my height I'm a 181 but based on weight I'm a 176. I know its not a huge difference but I'm probably gonna get customs so I wanna be sure about the length since I won't be able to return/exchange.

tldr: 5'9", 145 lbs, moderately aggressive east coast skier. 176 cm or 181 cm Magnus 102