I have tried both of these skis, both fantastic. I tried the 165 and they were a great length, i am also 5 6, an easy ski to handle, just all around good ski. The mike nicks are slightly harsher, especially for lines, but the full twin can be useful (the tail on the tm is enough to get you around). The only real reason I got the mike nicks in the end was the price, but i f you are getting them cheap then go for the 165 TMs, I did try the 175, way too long.
I haven't changed my signature in quite some time, so I will change it. Here it is.
yeah 165 is way too short, I like size 180. I had last years concepts in that size but this year they dont have the trouble makers in 180 which sucks. I guess they will make them in 182 but they dont realease till mid season or something.