Sure burst has the highest damage per clip. But with so long to empty the clip, reaction time of the guy shooting and bullet travel time, you never do end up emptying the entire clip before armor is rebuilt - and if you do, you're fighting the wrong enemy. If you wanted to have a good damage per clip you would have chosen a light flak, might as well use the banshee to what its good for which is the harassment fires and greater damage before armor drop.
You might as well use normal over burst in my opinion - You guarantee more shots going in the hull because no decrease to fire rate and you have a plus of more fires per sec. Because lets face it, if you're using a banshee you are using it as a harass weapon and not a kill weapon, sometimes even a support weapon - with that in mind you don't need that extra 70-80 damage you get per clip with burst, you need a quick way to dish out damage with your engineer for him to go back to repairs quickly(if you're using it as a support weapon) or you use it as harassment, and then you just want high fires/second stats and burst is not the way to go.
I will say though that if for some reason you still want a banshee for kill weapon the only viable target to use burst banshee on is a galleon because long rebuild times still allow you to empty the clip.