http://www.psphacks.net/forums/viewtopic.php?t=6963
seems u can upgrade back to 2.00 if required..
see the post below...from the forum
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can CONFIRM flashing you PSP back to 2.0 works fine and so does downgrading back
Tested on Australian 1.52, flashed to 2.0, downgraded
then flashed BACK to 2.0 using the firmware included with my PSP, then I downgraded for a 2nd time back to 1.5, and im currently playing DeathJr via UMD Emu 0.8c heck its the first time i've played a game on my PSP
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I know this has already been posted as being possible, but if people are like me... they want to be sure.
I had been holding off on the 2.0 upgrade until something like this came out. I saw this as being a perfect opportunity to try 2.0 out.
So... I have SUCCESSFULLY upgraded to 2.0, downgraded to 1.5, upgraded back to 2.0, and then back down to 1.5 again with all my homebrew working for 1.5 still.
Thanks to the creators.
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excellent news...
THANK YOU MPH AND SXT