Re: How long did Nolans Batman actually fight crime?(SPOILERS)
I read somewhere that it must've been about 5 years that he had the BB suit. I think it was in one of the art books. It was a note "Bruce" wrote, saying that after 5 years with the BB suit, he needed something more flexible, hence the TDK suit.
So, assuming this can be considered canon, it's 5 years, and a few months, considering the events of TDK and TDKR. Plus, Blake mentions Harvey Dent day being 8 years later of Batman's last "confirmed" sighting, so maybe Bruce was prowling the streets anyway, taking down smaller criminals?
If any character has ever earned the right to enjoy a happy retirement, it is Bruce Wayne. Nolan ought to be commended for caring enough about the character and believing enough in his own vision to provide a definitive, satisfying ending to the story of an ordinary man who turned tragedy into the motivation to accomplish something extraordinary.