I’m not trusting my root partition to btrfs at all. I don’t want to freely bash btrfs because it has its place on the opensource OS space but, when I decided to go full ZFS, one of the reasons that made me do this was that out of nowhere when booting my laptop, btrfs started to print out errno=-5 IO failure errors in an unrecoverable fashion. Volumes and sub-volumes would not even mount as read only, and after extensive(2 days) research I decided to let go and format that drive.
btrfs “dont need fsck” until you face some serious issue like this. What is the KASLR issue your are facing, that is making you to reconsider using zfs as your root filesystem?