It was suppossed that once you have 4 tier bonus RB should outperform BD by a large margin. But if check some logs the top parse/ranks destrologs are still using BD even having 4 tier bonus, is it due to having less margin of error? I've only got the 2T bonus and im running BD in most of the cases due it's easier to play and imo you have more freedom (i just use destro for 3-4 bosses).