> People don't usually understand that apt allows you to configure multiple sources across versions simultaneously, so you can e.g. run stable, but also selectively install from backports or unstable.

Which is just as well, because that's not generally a good idea unless you really know what you're doing:

https://wiki.debian.org/DontBreakDebian#Don.27t_make_a_Frank...

Granted, the kernel is probably the best thing to do it with, on account of their aggressive stance on compatibility and the narrowness of impact (no .so files in play).