Was thinking about the Origin 176, but at Keystone this year I was on 172 Rustler 9s and I found that length just visually intimidating skiing in the trees!
Meaning too short or too long? To me that would be way to short. You probably mean too long.
I have skied the first generation Liberty Origin 96 in 176cm, 182 cm, and 187 cm. I am on the 187 cm ski and its my all time favorite tree ski and I love it in bumps too. I think the 182 cm length is the best performer of the three and would recommend that for you. At 180lbs you will need it. At 150 lbs, the 176 works well. IF you really don't care about stability at speed, you could ski the 176. Realize they ski very short due to lots of tip an tail rocker.
The 96 is a much stiffer ski than the 106 and can't really be compared. The 106 floats a lot better, but I find the 96 planes up in deep snow and is very easy to ski. Plenty of float in the trees for me at 250 lbs. Its not my powder ski, but it sure pivots easy and quick, as well as carves a good turn when set on edge.
The Genesis is the women's version and I don't know if they are the same in the same lengths?
Another good tree ski is the metal less Blizzard Brahma, not sure what its called now. That you could ski in a low 170ish length.