I've been riding the D616 tires for about 600 miles now. After the initial break in period they handle pretty much like any other street tire in the dry. In the wet they handle better than the Q2 does. For example when going around a 35mph marked corner on wet surface at a spirited pace the Q2 will tend to slide. The D616 slides less. You can still break it loose in the corners and I haven't found really what the limit is, but they are better in the rain than the Q2.
How much better? Its really damn subjective. Sorry. I can't really find the limit without risking my wellbeing and the bike, I'm not that brave or talented. All I can do is push a little bit harder every time and see how it reacts. I'm thinking about doing an April trackday (IE a raining trackday) to see how they are in that kind of riding.
