You can use the NO-KXploit patcher and everything will run on a 1.5 regardless of the folders. Give me a sec to find the link for you...

---EDIT---
here's the link: http://www.psp-hacks.com/file/413
Put in the the game folder in your memory stick, run it, and enjoy all your homebrew. NOTE: the patch will remain in ram (meaning you don't have to run it again) untill:
A) A app causes your psp to crash causing letter B to happen.
B) You hard reboot (not sleep) your psp.

By the way, the reason you are seeing less compatability (now) is because 1.5 needs a hack (that two folder thing mentioned above, I'm not goinjg into details of how it works) to run homebrew. This patcher alows you to not have to waste the time to convert all of your old homebrew to something that 1.5 will boot, at the expence of having to re-run it from a cold start.

My personal opinion is that 1.5 is better then 1.0, because alot of homebrew is 1.5 only. For example: iso loaders, devhook, the dynamic version of PSPRadio, etc.

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