This is so awesome. I've always known that Scrooge was badass, but I never thought he was that badass :D
The guy who has cheated Scrooge, though Scrooge never finds out his name here, turns out to be yet another figure we'll see more of in years to come, namely his perhaps biggest rival: Flintheart Glomgold
No offense to the Don Rosa tradition, but I always found Flintheart completely uninteresting. I'm all for Rockerduck! :P
I'm possibly biased, because Flintheart is completely obscure here (seriously, he never appears in any stories, none at all; I read Disney comics all the time as a kid, and the very first time I saw Flintheart was in the Ducktales cartoon, he only ever appeared in that show), whereas Rockerduck is very famous and appears in Scrooge stories all the time.
Then again, bias aside, I'd take "worthy rival" over "bitter enemy with no redeeming qualities whatsoever" anyday.