Based on Apple's documentation, I assumed my 2008 iMac (iMac8,1) maxed out at 4GB RAM but just the other day I noticed in an iOS app called "Mactracker" that the maxium was actually 6GB. A quick Google search popped up numerous articles and forum threads saying it was indeed possible to upgrade to 6GB. One of the links brought me to Other World Computing.
I am a pro photographer and my iMac is the primary machine for my work. Apple's Aperture and Adobe's Photoshop are a few of my tools I use daily. For the last year or so, my machine has been memory constrained and I have been waiting for new iMacs to be released. Activity Monitory clearly showed I was out of RAM and there was plenty of paging happening.
I was skeptical about the 6GB upgrade but after reading numerous posts on the web and the excellent reviews at OWC, I took the plunge and boy am I happy I did!! I knew extra RAM would help my performance problems but I never realized just how much. It's like having a new machine! I am thrilled!
I can't speak to the durability of the product because it's been installed for less than 30 minutes but the quality seemed good and OWC shipped it promptly.