Red dragon might be the best marketed coral but not even close to the hottest IMO.
I've got maybe a 3" mini colony (frag) that I've grown from a 1" frag. I agree its nice...just not the hottest. Also I have never been able to acheive the deep coloration that I have seen on a few pics......even with it on the sandbed. I think this is pretty common too....Have you seen the RD in person? I was skeptical of it's "hotness" from just seeing pictures of it. I can say, now that I have it and in person it is stunning. Definitely hot! It is so fine and delecate it is unique in it's own (the finest branching acro I've ever seen). The colors are great too, red body, glowing purple tips, and white thread-like polyps.