We discovered the issue with scratched disks after 10.6 experienced some serious problems with a Helvetica Nueue font, at which point we tried wiping the system installing 10.5. When our IT people couldn't get 10.5 to work, we tried 10.4, only to find out that the brand new, 2700 dollar 27" iMac decimated both disks.
The fact that Apple considers this user error and not a real issue with the hardware is insulting. A year and a half ago, my brand new 24" iMac had to be returned and eventually replaced with a newer model, and I've had numerous issues with battery swelling on my Mac Book Pro. Now this problem, which comes with an extra kick to the butt, considering I had a "genius" tell me to be more careful about inserting my disks. Guess what, Genius? I've been inserting disks in older iMacs the same way for 2 years, and never had an issue with scratching.
I have been an avid supporter of Apple since I started in the design industry 13 years ago, but lately, due to the increasing shoddiness of the products and the level of humiliation and condescension I experience at the genius bar, I'm seriously considering wiping my hands of the brand and buying a PC. At least I can anticipate the crashing issues, and buy an external drive for regular backup.