You should also be using 6 inch shank burrs. You need some way to control the speed of the burr when you are using the long burrs. If you can't slow down the grinder, they will helicopter on you and the end result for you and the burr is not good.
I've seen guys using short burrs doing bowl work nick the seat with the part of the grinder that tightens down on the burr (that's a highly technical description because I can't think of the term I want). Plus, the grinder and your hands get in the way with short burrs. I just taught myself to use long burrs for everything any more.