I've been given a brand new 90/90-21 Metzeler 6 Days Extreme tire. Does anyone have any experience with them or care to offer an opinion? I run about 90% street (around town) and 10% dirt trails. I'm currently running Kenda K270's. They're about 75% gone and I was planning to try something more agressive like the Pirelli MT21, Kenda 760, or Dunlop D606 (have recently seen some negative comments about D606 wear patterns). I'm concerned that, though the price is right, the Metzeler is going too far.

1995 XT225 Cobra exhaust - Town & trail
2006 GSX-R1000 - Highway