To find out I may make a virtualbox image and try it myself, but just curious if someone already tried switching. This need may appear if someone wants to switch from the generic to a processor specific subarch. I would like to know if it is possible to do a clean switch, i.e. without leaving remnants and effecting system stability.
One way I can think of is:
1. boot with SystemRescueCD
2. get the list of files contains in the original stage3 file and use that to delete files on the system. One question here: how can I find out the correct stage3 file's subarch and version if I don't have the original tar.xz file?
3. unpack the new stage3 file
3. something else?
Reading this gave me an idea that I will have to recompile all the installed package over again.