Sorry, I have a couple of nitpicks. The starbursts have a bit of the jaggies, and I think your choice of using only a 600 pixel size instead of the 720 allowed may be part of the problem. More resolution allows for finer detail.
Yowza!! Wonderful image - the white are right on the edge, the star effect is a very deft touch and the colored arch shadows are - unbelivable. I completely understand your reluctance to put a font on the image - it wouldn't do a thing for the image at all. This would also be a great Chamber of Commerce image - might want to see if you can seel it to them. :>)
I don't have sufficient words to explain how I feel about this image - wonderful will have to do.
Nice scene although the flares are a bit overdone for me.....sometimes less is more. I think text would have helped your photo too since this is a postcard challenge.