I have ridden several 100 miles on a rocket III with a Riken Raptor 225/55R16.
It corners fine. As hard as it is for me to wrap my head around what I just said....IT CORNERS FINE.
My problem is when the bike is straight up and down. If the road has a slight crown, the bike "crabs" to me. Feels like it's rolling slightly askew. It feels like I am riding in a constantly changing side draft. I found myself counter steering all over the place and my arms were sore very quickly.
My father in law has 10k on his darkside tire and for him, he's said it's the best thing he's done. He rode it 780 miles one way in a day on it and loves it.
Personally, I think it looks like ass and I don't care for the countersteering....but it's his bike and my Vmax still walks all over it. :-p