I love Rocky and Bullwinkle too. So much so, I have all 5 seasons on DVD. So I hope that carries some weight when I say.
This is fantastic!! I do not believe you have changed the spirit of these characters by doing them in your style. I see touches that, though drawn different, still preserve the spirit of the original creativity.
Even though, in the series, most often their partnership appeared as rock solid. There were moments in which Boris and Natasha showed they could stab the other in the back. So I love the bombs behind their backs.
I think art and personality is true to the original creativity of the show. (this one's a fav)