this subject is mainly preference. both ways of feeding are fine and bp will thrive either way. both ways also have to be done correctly. there is alot of pages on this subject, using the search feature should bring them up.
aggression is not from feeding live or frozen, i've had bp's attack frozen just as much as live. aside from smell bp's can also detect minute changes in body temps with their heat sensors, they can detect the warmer areas of a rodent and "see" a thermal image as well.
vaughn