I personally don't think the colors make any real difference in warmth but, certain colors may make you psychologically warmer or just make you feel good about your quilt because it looks good. Of course, as has been stated, if Richard Nisley jumps in here, just ignore what I said.
I do think black is practical on at least one side for sun drying. I once made a two color quilt using my college colors; because of that, I think it's the best looking quilt ever ... orange & blue ... Go Gators :-)
So, the "red" got vetoed. Just goes to show you, us guys have to answer to a higher power. lol
Good luck with your project. Looking forward to some pictures!