I've been holding off on upgrading past Snow Leopard because my drive was nearly full and I had some legacy programs that wouldn't run on Lion. With Mavericks available for free, I decided to take the plunge. I replaced my internal 500 GB drive with a 1 TB drive and partitioned it with Snow Leopard and Mavericks partitions.
I was delighted to have the rubber enclosure to keep my 500 GB drive. It gives me comfort to know I can go back to that drive if necessary.
Installing the new hard drive in my mid-2009 unibody 17" MacBook Pro went smoothly. I ordered the toolkit that contained a 00 philips screwdriver. The MacBook itself is a piece of art: such tight tolerances, but easy to open and access. I took my time and followed the guide, and I did not experience any issues.
A trick I learned a while ago when disassembling items with small screws: I attach a piece of masking tape to the table sticky-side-up. Then, as I remove the little screws, I place them on the tape in order of removal. Even a hearty sneeze is unlikely to send these little buggers flying.
Sorry, no photos.