Sorry, I just think Shemar is too pretty to be Ranger. Ranger is manly and not pretty. Plus, although Shemar is about 6'1", he's still not as physically imposing as Ranger needs to be. I'd love to see an unknown in the role. The character is supposed to be mysterious, so having an unknown actor playing Ranger would work.
Like I said upthread though, even if all of the other characters are cast perfectly, the movie will still stink with KH in the lead.