Only mid-20s? I've always seen him as starting younger and being older than that. I like to think of him as being 29, since that was the age TPTB had Bruce as for basically ever (Frank Miller pitched DKR because he was turning 30 and couldn't deal with the fact that he was going to be older than Bruce), though I suppose he started earlier than that, so mid-20s might fit Dick better.
As long as they don't forget Babs was a few years older.