I have first-hand experience since just last week I went from an old set of 1* upright Ping Eye 2+s to a fitted set of 3* upright Ping i20s. After two trips to the driving range, here are my impressions: The i20s feel better. Eye 2s always felt like I was hitting rocks. Both sets are equally easy to get up in the air whether I hit it fat or thin. Maybe the i20s go a little higher on thin shots. The i20s are more punishing on hits toward the heel or toe but more rewarding on hits in the center. I can draw or fade the ball with the i20s which I couldn't do with the Eys 2s.
I was hitting the i20s up against the JPX-825s and chose the i20s because I liked the feel a smidge better.