I happen to have the Alpha Pioneer DC Plus. I'm happy with it except for the creep problem. That's when the towers move a little while you are stringing the mains. I had to make my own creative modifications to address the problem, which I discussed in a previous post. Another issue that might be important if you string racquetball racquets is that the posts for the top and bottom parts of the head only go to 15" apart maximum distance. Many racquetball racquets are longer than that. I don't know if those same problems are associated with the Gamma or not.
I think the biggest advantage of the Alpha is the linear gripper. It works quite well and makes the job easier and faster. You basically just slide the string into the gripper and it tightens by itself once tension is applied. For me, that was the best reason to go with the Alpha, but for you it doesn't seem to be important, so maybe the Gamma is a better match for your needs.