OK, so I am another person with with the perenniel "ski length" question.
I, too, am trying to decide between the 177 and 184. I probably ski about 70% on-piste. I weigh the same as the OP, but am a bit taller (6'3"). I've demoed the AC50 177's in hardpack/ice (mostly ice) at Collingwood and they were awesome for me. There were no 184's to try and I've never tried them in deeper stuff, and I do go out west a few times a year.
The local store is clearing out and 177 is the longest that they have and that's what I was thinking of getting b/c of my positive experience with the demo. But like I said, I didn't try a 184. When I'm out west, I prefer the steep stuff, so I figure that the 177 might work better for that, too. But i'm fixated on the height thing, even though I think that weight is probably more important. Stick with the 177's??