I believe these are accurate, though, again, the extra hardware they don't explain will play a major part in what Durango does. I've also heard from reliable sources that the GPU CUs are super-efficient, with an aim for almost 100 percent usage at all times. The 360 hit around 60 percent, I understand. Like I've said previously, context is going to be really important for both systems.
Now please explain to me where your 170-200W figure comes from. I see absolutely nothing here to indicate such a thing. Durango really sounds more along the lines of a cable box/tv tuner than a games console.