Finally I'm installing Mac OS X on my 27" after putting in a Samsung 840 Pro and an extra 2x8GB Kingston ram.
The disassembly went quite well, nothing mayor to report of. The small display connector was a bit tricky though - remember to lift the small lever (with a tab on it) before removing the cable, the power source is easy enough. Once in, the old tape removes easily from the iMac and the display and I put something else on. It's not perfect right now and I'll will try something else from my local hardware store soon, because the selection of 3M products are very limited in Denmark apparently. Looking forward to the "real" Apple tape - no doubt that this is totally custom, because there are quite a few "bumbs and turns" on the inside of the iMac, which makes it impossible to copy perfectly - they will know that you've been inside....
Had some difficulties booting up, because the iMac believed that my USB thumb drive (with the ML installer on it), was the primary boot drive. I researched the internet, and found out that this is because of the missing Recovery partition on the new SSD, which is normally located on the standard drive. Using the Recovery Tool (CMD + R on startup), you will be able to download ML from Apple and install it on the new SSD drive directly (remember to format / build a partition on the new SSD using Disk Utility in the Recovery state first) - this took a while to find out, but glad that it didn't mean that something had gone bad.
I will do some tests of the standard 1TB Seagate drive and the new Samsung 840 Pro tomorrow
Now: time to sleep!