This is a very rational, common-sensical statement. However, don't most of us find in practice that as little as 5cm can be the difference between "this is okay" and "wow"? That's why there is so much hair tearing over the Kastle 10cm gaps.
I think gunnerbob's question is reasonable in that if you put a 177 with a short wheelbase up against a 180 with a long one, you're skiing two significantly different lengths. Not saying that's the case with these two skis; just putting myself in his boots.