Translation to 3.P takes all of 30 seconds when building a character, but it's a pain to write the classes to be directly 3.5 and 3.P compatible as you'd need to write skill lists and things twice. It's also easier to go from 3.5 to pathfinder than the other way around, because 3.5 is simplified to pathfinder, so there's detail loss.

May I recommend getting a new thread with a billion reserve posts? There's a lot of homebrew that should still be added, and several of the existing ones could use class feature tweaks, rather than using the base's features exactly.