I just got rid of the stock rubber and mounted a set of Perelli Angels on my '11 C14 (got 4,500 miles). Put in 350 miles today through the central Colorado mountains and these are my initial impressions (comparisons are to the stock rubber):
1. Significantly lower counter-steer effort needed.
2. Way better feedback from the road.
3. "Lighter" handling feel, especially when transitioning from turning one direction to turning the other direction when in the twisties -- the bike just moves very naturally from one lean direction to the other.
4. The tires do not follow road seams (I found the stock rubber very poor in this regard).