SWAT 3D is a pretty good game,....yes, you can assign different weapons to each member, along with different uniforms, secondary weapons,ect ect. AND,....there are ALOT of mods you can download for the game to add a WHOLE SHITLOAD of new weapons, enemies, uniforms scenarios ect.
As far as Operstion Flashpoint,....All I can say is "WHOLLY CRAP! DOES THIS GAME ROCK" there are a buttload of mods to download for it also, I have spent most of my time creating new missions, and scenarios. once you get the hang of the mission editor you can do all sorts of stuff. : squads parachuting or fast roping out of helicopters, beach landings with the patrol boats, Russian and U.S. forces on the same side fighting against the Resistance, armed civillians, TOO MUCH TO LIST.
The Rainbow Six games are awesome too, and there are alot of mods for them as well.