Reds will give a faster paced race, but to lovers of the chase, a grey race makes for better music. Lots of twists and turns. With ample cover, a grey fox can punish a pack of hounds (he can fit places they can't fit easily). Unless there are coyotes around, then your grey race lasts around a minute. If he is not in a place he can stay in thick cover that coyotes can't fit through, then he is not far from a hole and he knows how to use it. This is the attraction of the pens to houndsmen. In places over-run with coyotes in the last twenty years or so, it is a place where you can actually get fox to run. Doesn't have deer, doesn't have traffic, two very important considerations as well. It is my experience that if you can find a red outside a pen to run, your dogs are going to be in a lot of traffic, and if they survive that, they are going to be in somebodies yard barking under a shed. Coyotes run good, but outside of the wire, the race goes out of hearing too much to be enjoyable. Inside, they run fast and in big circles, and when they get tired they tap out to one of their buddies. Strings out the dogs, and splits them up. Grey fox keeps them all in a nice tight pack. Grey fox will teach dogs to follow a track way better than anything else, if you are looking to train pups.