I currently own both a Fusion and a Santi. The Santi is a little easier to put on, and definitely easier to zip by myself. The pockets are MUCH nicer. The suit is more pleasant to wear with the top of it down, as one might between dives on a warm day, because the suspenders hold it up better and the pockets don't sag as much. It has color, which makes me more visible, which I like. I have the E-lite, and it dries very, very quickly -- much faster than the Fusion Sport, even, and far faster than the Tech.
And heated gloves... I hear!