I've run Dunlop D404's up front since I went Darkside. The Metzler front started to cup severely after just a few thousand miles so I mounted my first Dunlop. It lasted about 11,000 miles before I changed it a thousand or so early (leaving on a long trip). My second D404 lasted another 12,000 miles. Again, changed it a bit early due to a planned long trip. My third is doing well. I've never had any cupping problems like the Metz.
btw, still on the original darkside Riken Raptor ZR after 26,000+ miles. Getting close to changing it but might run it to 30k for grins.