Back in my days of full time sports shooting, I would routinely purchase Canon refurbished lenses from B&H (no offense Adorama). I NEVER had ANY problems with my lenses and paid 1/3 of the retail value. The warrenty was only 90 days, but when you can purchase $4000-$6000 big glass for $2000-$3000, it's hard to resist. As far as quality...it was explained to me by CPS that a refurbished lens is dissasembled, inspected, assembled, adjusted, tweaked, and tested again for quality. In essence, the refurbished lenses are better and more reliable due to stricter "hands on" quality assurance. But that's been MY experience. I mean, were not talking about already cheap plastic vaccuum cleaners from the online shopping network. Were talking about precision instruments.