I'm really alerted to hear about the many problems, the last upgrade of Sabayon has lead to, though, I must confess, those problems did not happen to me.
Anyway, we all know, that Sabayon is a rolling release and any changes in graphics, kernels and drivers can lead into serious problems. And because I know this due to own experiences, I always do a backup of my system before I do an upgrade, at least, when there is a change in a kernel (no matter main line or in within a main line), in drivers (wlan, USB, graphics...). You can check the packages to be upgraded in Rigo.
So, I highly recommend you to make backups. What you need is an externel harddrive, 500GB or 1TByte. And you can do backup with a script, adopted to that, what I have published here before:https://forum.sabayon.org/viewtopic.php?f=76&t=30597&p=166834&hilit=backup#p166834
As I say here, you can adopt for your needs. You can make backups for 5 generations and then delete the oldest before you backup again.
In (emergency) case, you'll need to restore your backup, you can use a simple Sabayon Live system (on USB stick).
If you are interested, then I would describe in this forum, how do I restore a backup, keeping in mind old UUIDs and others.
p.s. There was a serious problem with my USB3 external disk connected to a USB3 plug (of computer) with Kernel 3.13.5. I use this USB3 disk only at USB2 plug now.
-Linuxfluesterer (I love KDE ...)