Been wearing the Q2's all race season with clear lenses, switching to the crystal green with the green lens on overcast days. my opinion, tifosi make some pretty nice glasses for the price. decentered vented lenses gives you a non-distorted view without fogging up, and the frame of the Q2 allows for max periphial vision -- very important features when you are screaming through tight single track. also use the quam 1.5's when it gets sunny out as it comes with 3 lenses and the sweet adjustable nose piece they just added this year. check out the link above for the tifosi site, or do yourself a favor and just order up a set at SPEEDGOAT.COM
you can also check out the speedgoat blog (and do a search for "tifosi") and you will find my full blown review of both the Q2's and the QUAM 1.5's.