Reading your report, Thomas, I suspect the A2A wil have a different (more realistic, probably) fuel consumption model than the default FSX one that I flew (and on which those rough calculations were based).
Your approach to planning and route seems pretty much consistent with mine, although I chose to do a few more legs of maximum 5 hours - and use speed accelleration for parts of the cruise section; FL compensates for that nicely up to 4x speed)
I flew at 2250 to 2300 rpm, as low as possible (better range with the same wind conditions), unless higher winds seemed more favourable. Usually, the lower altitude meant less headwind.
Also, I used IvAp's weather engine, which is sometimes way off with ActiveSky, I noticed with the Alaska Event.
So there's plenty of differences that could explain the difference in fuel burn. As it turns out, you had the best combo of them all!
I awarded the medal to the top three, instead of just the number one, because there was such a big difference. So there must have been some discerning factor in there (my bet is still on the A2A consumption model), other than mere planning and execution. And my estimation is that, regarding planning and execution, the number two and three must have performed on a similar level.
I see, by the way, that the awards do not appear in your Avatar, nor in Trevor's, even though I manually awarded them. If they don't appear in 24 hours, I will have to investigate what went wrong there...