If you are jibbing around, then the 176 is perfect, but if you are only hitting huge ass jumps, i would size up to the 182's as they have more stability. As far as durability i have heard that they are bomb proof due to there thick edges as well as good half cap, half side wall construction. As for the price, the fks new cost 400, and new alpha 1's from lat year are also probably going to be near 400, so u are looking at a potential of $800 new. But to cut some of the money of, you can get the 140 fks as you only weigh 140 lbs, and that is plenty binding for you!
I'm still using my 2010 alpha 1's so they are definitely durable! Plus they are a ton of fun to jib on. Only problem I've had with them is a little delamination, but that didnt happen until this past season and Armada has improved their top sheets since then so they should be perfect now.