I have 189s and I'm about 5'11, 185.  Last winter I was about 200 or so (drank more beer as an undergrad).  You do need to be pretty strong to rock them right, but you seem like you will be strong enough.
I like heavy skis.  I think that being able to push the skis into momentum makes them ski better.
I have not been on the 179s though, but they just seem like they would be too short.  I didnt really get mine for jibbing as much as charging, but in powder you are able to pop around on them pretty well, it just takes more muscle.
I ski sierra cement, so the longer the ski, the better it floats in the thickness.  also, it has been my experience with bein nimbly bimbly in the pow stuff, the bigger skis make it a little easier because you maintain more float and have more ski that you can push off of the snow to create popping power (think wakeskate/wakeboard ollie kinetics).
I think you will be fine.  They will feel huge at first, but after a few runs, when you are used to them, you will think they are the sickest things ever.
Good luck.