On the flip side, it probably helps if good role models are willing to take their chances in establishing their presence in an at risk community. Change has to start somewhere.

Sure, that's called gentrification.

Reduced crime is one aspect of gentrification, but generally it's a changing demographic as people get priced out of a neighbourhood.

Yeah, when I hear "bad neighborhood", I think more of property related crime, graffiti, loitering, abandoned/neglected houses, etc.