Every (current version) PSP is now downgradable and unbrickable and no future firmware can chnage this fact!

http://forums.maxconsole.net/showthr...697#post645697

The battery lets to downgrade any firmware version (including those that Sony releases in the future), and to unbrick bricked psp's (whatever bricked by software psp, not only the ones bricked by that retard of Serafin), in all current hardware. Of course, we cannot be sure about future hardware, but the Firmware Update game has finally come to the end for all current psp's.
Only minor downside, you need two batteries, one that is configurated for homebrew (a so called service-battery) and one for regular play. A good excuse to pick up the 2200 mAh battery and use the default one for "service".

Fredi