I was just thinking. The Doctor was programmed with the knowledge and experience - and, conceivably, personalities - of 47 (there's that number again) medical officers. Do you think it's probable that one of them was Leonard McCoy?
I'd say it's more than likely. They both have similarly grumpy personalities, and the same dry sense of humor. And then there's the frequent use of the "I'm a doctor, not a..." line. Plus Lewis Zimmerman's pet iguana's name was Leonard. Obviously, a lot of the Doc's personality is based on Zimmerman himself. But I like to think that Zimmerman had a certain admiration for McCoy, and programmed the EMH with certain aspects of his personality as well.
What do you think? Too much of a stretch?