Okay, so I have spend a grand total of about 30 minutes in my Moment (it arrived today). I tried it with a NeoAir XTherm (183 cm long) and it was surprisingly roomy. I could almost sit upright which is actually pretty rare for me. I'm 186 cm but seem to have a long upper body. I liked most the design of the head and foot ends because it does a very good job of keeping the inner wall away from me. As far as I can tell by now the vestibules are large enough and I think if I needed more space I could happily use the inner in the smaller configuration and still have enough room. If your shoulders are very wide you might get a problem. But I almost never lie on my back, so I didn't really care if it was wide enough lying on my back.
Given the paper dimension I was actually surprised how large the useable space is and the liveability (is that a word?) seemed pretty good. Much better then my Akto. I plan to use it this weekend, so I can probably say more on Tuesday or Wednesday.