The requirement to downgrade is cause version 9.2 has a exploit in the arm9 security needed to use the features, the use of it is to install the arm9loader hax that is part of using CFW To enable unsigned content to be used. Like PSP CFW.
There is two options for using CFW but both must start on 9.2 system version as is the only way to allow access to any othe way.
Emunand is a clone of your system data but stored in a partition on your sdcard, and is used as a CFW only clone, instead of Legit system.
Most people would just follow the process to install a9lh as it enables cfw all the time and is less fustration and hassle cause is 100% funtional as apposed to some not 100% work arounds.
A example of EMUNAND is the psp pro cfw where if you were on 6.61 you would need to use a fastboot enabler in order to use cfw everytime system shuts down. (NOT SLEEP) of course this is before the psp infinity patch was made to allow permenant patch of CFW.
In short Permanent psp CFW is the equivilant to A9LH that most users here use and the guide provides the process to getting it on your system.