There really aren't any down sides to it as long as you don't cut it too short. The main purpose of the cut is for aesthetic purposes really. It doesn't offer much in the way of performance unless you wanted to get real technical then it could increase the cycle rate a little bit due to the reduced weight of the bolt.
CCI PHANTOM PRAYER: Our Phather, who art in Oregon, hallowed be thy name. The game shall be won, by your perfect gun in the woods as it is indoors. Give us this day our Nelson valvetrains, and forgive us our autotriggering, as we forgive those who autotrigger against us. And lead us not into semiautos, but deliver us from electros. For thine is the 12 gram, the 10 round tube, and the pump action, for ever and ever. Amen.