Thanks a lot for your kind comments. I was out shooting 4 days in the Japanese alps (4*5 this time ) and only got back in town this evening.
There really isn't anything secret about the way this was shot. It was already light enough that the shutter speed was fast enough to be able to take many images in a short amount of time.
I took 3 to 5 images at each angle (-1, 0, +1 and some hiding the sun to avoid flare). I must have taken less than 2 minutes to shoot all the images. Luck comes in through the fact that I didn't forget to take any of these although it was only 4:10 AM.
The post processing was a lot trickier since I tried this time to prepare the images in PS before sending them to PTgui. At each angle I superposed the lighest and darkest image and applied a hand edited gradient between these 2.
This alone wasn't enough since the sky got way too dark in the left part of the image. I decided to simulate a stitch in PS by positioning the images approximately. I did then apply a second left to right gradient in multiply mode to increase the weight of the lighter image towards the left end of the image. Finally, I had to copy parts of that mask back to the individual images.
PTgui did hence a great job at making this look pretty seemless. I had to play a bit with the control points, but that part didn't take too much time compared to the PS work.
Hope that it helps,