Marvel Diamond VS DC Diamond

I just noticed that Iron Man's diamond (Extremis armor) is just like the Superman diamond. I guess I never paid close enough attention (mostly because I don't read Iron Man), but after seeing some news about Iron Man 3 concept art showing more elements of the Extremis plotline, I did some googling. And the chest "symbol" that came up just jumped out at me.

I'm sure I'm way late to the party, but I'm just curious if this was ever an issue. If there was, I missed any of the nerdrage that popped internet blood vessels.

Also, I understand these particularly-proportioned pentagons are commonly used as diamond symbols (jewelry not playing cards). But I guess I thought it was interesting because I don't know any other hero who uses the diamond silhouette as part of their symbol. Granted, lots of heros have circles and triangles in their symbol, but I would classify circles and triangles as much more generic shapes that are much more prevalent than pentagonal diamonds.

If there are other heroes who also utilize the diamond, please enlighten me!