As if the name ("Iron Man") and the lack of a steel insert for the splines and the weight and THE FACT THAT IT SAYS 4130 RIGHT IN THE DESCRIPTION weren't enough, somehow I still assumed the S&M Iron Man sprocket was made of aluminum. And we all know what happens when you assume. So, apologies for that. Still not sure how I feel about the individually drilled teeth (and the fact that they're 3/32"), but I'd be totally down to run a chromoly sprocket. I can't at the moment since I run Twombolts, but I suppose we'll see how this all works out. (For the record, I'm totally in favor of eliminating the sprocket bolt -- not for weight savings, but in the interests of spreading stress evenly and cleaner design.)
I just looked up "BMX" on Google Image Search and this was the first result. Maybe next time I should turn "Safe Search" on?