Just my opinion, but you are in Denver and your house will see significant snow loads! Maybe they could get away with "efficient" building techniques in Arizona or some where sunny, but I would be a little worried.
I don't know what your contract says for building techniques, but I would start looking into it.
I looked a little more into it, and went by the house again. It does have 2x6 studs, but I'm going to push the issue on the inline framing. If that issue is fixed, I have no worries about strength. My architect/builder friend builds houses, including a house for himself last year, in Salt Lake City using the same technique.
I talked to the inspector, my realtor, onebadgsx, and my architect friend,and all agreed that it needs to be fixed. I emailed the builder, so we'll see if I need to get my hands dirty next week.