I have used the 2.1 a billion years ago and I remember I really liked them. They rolled quite well while still providing good grip and they had a nice big volume compared with the trend back then. They had to be the tires with the roundest profile I have tried so you can really lean into corners. The only downside is that I thought they wore fast... But I was young student without too much money, I'm not sure how they would compare with what I ride nowadays. Do they make UST z-maxes?