# tazpkg set-release cooking
# tazpkg recharge
# tazpkg upgrade
more info on tazpkg manual:
http://hg.slitaz.org/tazpkg/raw-file/tip/doc/tazpkg.en.html
After upgrade you will probably have problem with kernel solved on this post
http://forum.slitaz.org/index.php/discussion/2152/after-cooking-upgrade-no-hardware-drivers-loaded-no-xorg

Is there any planned fix for the upgrade process or are we required to copy the vmlinuz file for the foreseeable future?

I upgraded yesterday and I think I encountered the above-named problem. Try to fix it...

Man does anyone test these isos before releasing them or is this all a Machiavellian comedy script?

Releases are tested for 3 months prior to release after a complete freeze on the repository. Cooking however is like Debian Unstable - untested and in constant development. It's generally not wise to upgrade from stable to cooking because of MANY changes between stable's packages and cooking's ones. Basically, the easiest way to break stable is to upgrade to cooking using an OLDER tazpkg.

You could say the same about debian or fedora's unstable releases too. In fact, I dare you to upgrade Lenny to the latest version of unstable Debian and see how well it measures up in comparison.