I'm also amazed by the capabilities of Sabayon for updating and upgrading.
I haven't been able to burn SL7 in a good CD because I hadn't. Tried a a couple of times and the cds didn't boot, bad for the cds. But I have a cd with SL 5.4 -k. 2.6.35- from a magazine. So I installed 5.4 on my laptop (double boot with crunchbang). Before doing the updates that magneto showed me, I went to the wiki and followed the instructions, starting by re-installing entropy, equo and sulfur previous upgrade of the system. It took 7 or 8 hours to be done all the upgrade plus checking the health of the upgraded system. Now I have a healthy SL7 Gnome with kernel 3.1.
I want to add that I have few experience with Linux and I did everything following the instructions in the wiki.