The truth is that you can play as every character in the game that you can command (So you can play with Agent Salter, Schumann, Soldiers from Sicily 2, Pilots from Libya 1, soldier from Burgundy 1, Ken Willis, the real Gunter Von Freiberg....) and the way how to play with them is to set your user settings (I mean multiplayer presets) not in game, but manually. Everything you can do is to edit your user_presents.def file - rewrite something. It´s all about manual choosing your character. It´s not allowed in game, but it´s "hidden" or "secret" in game files (these characters).
By the way for information - every soldier has his own Stats
For me this is a littlebit like a "Cheat" (but not hack!) - I mean cheat against construction of the game. I think (I BELIEVE!) that noone from =RpR= who knows how to play with another characters plays deathmatchs and other styles, I think they all (ofcourse We all) uses these "Tricks" only for cooperative. I don´t play with these characters often (but I know how to play with them), but anyone who knows me knows that I´m not "Score builder" or I´m not trying to be the best in team, so If I do, If I play with these special characters I do it only if I´m tired about those 30 characters in the list. For me I play this game since 2003 and I´m tired about these characters, because I know them more than my shoes. For me It´s only about variegation of the game. And I believe that everyone who uses this is on same boat like me.