Glade Riven
Adventurer
I'm liking some of what I'm hearing, but I'm disliking some of it too, so I'm still unsure about buying into it completely. With as many 3rd Edition books as I have (I literally have chests of books,) I'm not sure I'd want to dump everything in favor of starting over with what is still essentially 3rd Edition. I like some of the things I've heard via some of the various threads here, and some of what I've read, so I have some interest in taking some of the ideas for a 3rd Edition game.
I think the best way I can describe the Pathfinder changes is that it brought 3.5 core up to the power level of the late 3.5 power baseline and variety. And while Stormonu wouldn't recommend Book of Nine Swords, the martial system actually works fine with Pathfinder. Other than skills, I think the only change needed was to boost the HD of the swordsage up to be in-line with Pathfinder's BAB/HD ratio. Most people who play pathfinder want to avoid Book of Nine Swords, though, because it's too much like 4e and they don't want to play 4e (Bo9S seems to make Pathfinder more like Star Wars SAGA, to me, though). Other alternative systems brought out in late 3.5 should be fine.
Items & magical items can be used straight out, but it is a good idea to check with the Pathfinder spells for minor tweaks. The biggest changes were to polymorph type spells, which tweak stats instead of replacing it with an animal's or monster's stats. Things like Weapons of Legacy should work fine. Liber Mechanika from Iron Kingdoms works fine.
I would not recommend "downgrading" Pathfinder to 3.5, however. For one, Pathfinder is far more cohesive than 3.5. For another, I'd think it would be a bigger pain in the butt.
What are the exact issues with Pathfinder that makes you uncomfortable? Is there a specific product (or set of products) that you really want 'ported over?