I just downloaded Experimental Might 1&2 from RPGNow.com. I am interested in how to port some new ideas into my True20 game and my new setting. I am a huge fan of what Paizo is doing with Pathfinder to keep the OGL alive but 3.5e has left me a little cold. Too many rules and DMing a high level game is a pain in the rear. Hopefully Pathfinder can make higher leve gaming more fun...but that is for another thread.
However, what I am reading about in Monte's new books might be worth looking into for Pathfinder. The books contain combat schools (Fighting Domains), feat groupings (bonus feats, oblation feats, uberfeats), and this isn't merely adding new feats but adding ways to use feats that are IMO very interesting and would go a long way to making fighters more attractive without making them Wuxia (not my thing, sorry).
Then there are clerics, druids and wizards with a full 20 levels of spells which is extremely intuitive.There are spell-user disciplines which are basically spell-like abilities for clerics, druids and wizards. These are an excellent idea and add some nice color to the classes.
There us a lot like in there books and I really think that Paizo should take a look at these books and potentially include some of these both as core rules and potententially as optional rules in Pathfinder.
Hopefully this will happen with Monte on board.
As an aside, looking at what Monte Cook alone could do with some good variant rules for the classes. I have to believe the 4e was largely a money-making endeavor from WoTC. If Monte alone could do overhauls with 3.5e rules I imagine that with WoTC's battery of skilled designers a lot could have been done with the 3.5e rules that didn't require a new addition of the game to fix what was broken.