Have not gotten anything yet.
I must say that with your power feed and decent box size you are already miles ahead of the "chuck and duck" 4" shear bolt buster chippers. I really need the variable feed because I don't burn anything. I want everything to get fed in there, even if is REAL slow. So if you are thinking of chipping some 4" and up then yes I could see why you would want to upgrade. At 16.5HP (pto) you are even worse off than I am, so I would not expect to chip anything over 4" with any kind of speed. If I were you, I would not upgrade, unless you want to put it on a larger machine.
I must say that with your power feed and decent box size you are already miles ahead of the "chuck and duck" 4" shear bolt buster chippers. I really need the variable feed because I don't burn anything. I want everything to get fed in there, even if is REAL slow. So if you are thinking of chipping some 4" and up then yes I could see why you would want to upgrade. At 16.5HP (pto) you are even worse off than I am, so I would not expect to chip anything over 4" with any kind of speed. If I were you, I would not upgrade, unless you want to put it on a larger machine.