I updated and it works fine. However I get little scared by reading this thread. I never visited PS3NEWS, but I guess it must be really simple to make a proggy (virus) that does this automatically and then causes a a bunch of bricks. Also, someone mentioned that some other sites may cause PSP to brick too, which are those?
I will go back to 3.52 M33 to be sure as I love my homebrew PSP very much. No dis-respect to the M33, I just don“t want a brick because I missed out on some info in the homebrew scene, which I do quite often. Personally I think it would be enough to stop the XMB from working or similiar, not a total brick.
BTW: The home-menu is very nice, and would be even nicer with "reboot"-function and some way to change clockspeed in games. Then I would not need Custom Firmware Extender no more.