Every PSP can be downgraded using the "Pandora Battery" technique. You downgrade to 1.5 and then upgrade to the newest custom firmware. It's safe to do this as long as you get the files from a trustworthy source. You're right, there are some sites with bricking software, but the Pandora Battery can unbrick even those PSPs.
There is a load of cool homebrew for PSP - what are you interested in? Most people are in to emulated handheld games.
Jim