I have played with some. There are certainly some mods that will make Arma feel like a totally different and enhanced
game from default, in some aspects even better than OFP
The most simple of all must be the ECS. It changes AI completely by just a server side install, client side install optional for dynamic enemy speach and whatnot
*Introduction to ECS*
Quote:We've been pinned down by marksmen, surrounded by BMP's in a close quarter situation, flanked regularly by enemy spec ops, blown up, torn to pieces and ambushed many times.