When you restart, you will restart into whichever kernel you have installed, which may be whatever you booted into previously or a new distro kernel with the up

When you restart, you will restart into whichever kernel you have installed, which may be whatever you booted into previously or a new distro kernel with the updates compiled in. There are no Ksplice updates loaded until you tell them to load and Ksplice does not make any modifications to the actual Kernel binary, so #2 isn't really an issue. The real problem is there may be limitations on when you can reboot, leaving you in a vulnerable state. Sure, an ideal environment would let you reboot any system at any time, but those places are like unicorn ranches. I completely agree with your last comment, though: systems suffer from weird bit-rot diseases. If you never reboot, you may find things challenging when you finally have to. Disclosure: I work on the Ksplice team.