Yes, I agree, it is said by keslier in the first mistborn book that mistings are allomanciers that can only burn one of the eight basic metals, but he never goes on to elaberate on the others. I had an actual short story on a mistings who could burn atium, and it turned out to be rather fun to RP with, because not only did he see into the future a little bit but at a very slow burn it helped him become some what of a genius, as atium naterually increase the brains ability to intakce information.
I myself am curious, and would hope that it is true. In fact (SPOILER FOR WELL OF ACENSION AHEAD) up to the very last page of MB2 I thought for sure Elend would be one of the lucky few mistings that could burn atium, but was never discovered because atium was so rare it never would have acidently shown up in his stomach some how.
Few, I'm ranting, any who, back to the subject matter. I am pretty intrested in what others thought on this, though it seem that fellow forum members got sidetracked with the HP7 descusion.