If the angels are young and small when introduced, and grow up with the neons, shouldn't that work? although there may be a very slight risk of losing some neons, but if the angels are used to them and the neons are full grown there shouldn't be much of a problem.
If kept in large enough 'schools', ie 6 or more, the aggression is spread out enough that there is no real danger to an individual fish. Kept in a group any less than 6, then the fighting will be serious. I think in the wild they are a schooling species (correct me if I'm wrong). Most people just don't have big enough tanks to keep them like this, but if you have, then why not?