yeah i have been using role playing to develop my characters and stories for a couple of years now. it works great. especially if you really like the character
although my most tried and true method of creating characters is to take a single aspect of my own personality and develop a character around it. for instance my most resent character has a powerful sense of justice which i stemmed from my own desire to see wrongs righted.
this really helps me get into the head of the character because its my head to an extent. even if the character is a different gender or has a different moral sense than i do, if they share a single aspect of my own personality then i can relate to them better.