I did it in 1 hour and 18 minutes and I watched the Sun rise from the West. 
The only reason why it took “so long” is because I had no idea when to start descending and slowing down from Mach 8.5 at 130,000 ft. 
So I played it safe, but it could be done faster I’m sure.
I have to say that the Darkstar is the best thing that has happened to Flight Simulator in a long time, not diminishing the merits of all the great add-on aircraft and other updates of course. But I haven’t felt this excited by a flight for a long time – seeing the world whizz by so fast is just extraordinary, and all the data streaming held up as well! I completed the flight with live weather and all other online features on. Kudos. It was supremely entertaining.