I've been on a 64" since spring. I had been skiing a 67" old school XTR which I liked. I'm 5'11"/165#'s running into 38 at 34mph.
The WR is a great combo of turning ability along with stability behind the boat. I have a tendency to pull long and bring excess speed into the ball but the WR doesn't seem to care - it turns anyway.
I had to get used to how fast the ski is behind the boat compared to the 'old' XTR. Maybe its the CC technology, but my old ski was not that fast. Once i got used to the speed it can easily generate, I have been able to really work on an earlier edge change.
I haven't ventured too far off stock settings other than a couple suggestions from Chad Scott. Most of my adjustments have been small front boot adjustments.
Greatest attribute is definitely it's ability to turn. If I dislike anything it would be that the ski will launch/takeoff out of the ball when you load the line very quickly. I've taken a couple good spills because I wasn't in good position when the ski took off. (My fault, not the ski).