I do not believe Raiden to be an equal to Snake in Sons of Liberty. However that is what Kojima the man himself stated, and henceforth it is canon. I don't have the time to look up that old interview right now, but maybe later when I have nothing else to do I'll go look it up.
It's true Snake has a more impressive resume, but Raiden is no pushoever. Handpicked by Solidus himself and trained to kill since he was a child. Later molded and adopted to simulate Solid Snake. Again I do not really think they are equals, but given Raiden's performance in the Big Shell I can see why Raiden could be considered equal. Equal heroes? Raiden was just being a puppet, he was no hero at all. If anything Snake is the only hero in MGS2 by willingly getting in all that mess just to mess with the new Metal Gear and gather info on the patriots.
I meant Fox's exo-skelleton was the prototype, not Raiden's. Besides do you really believe Raiden would use a watered down, older version of Fox's exo-skelleton. I think not. Who's to say Raiden won't have Thermal vision in his helmet 😛
All right we know nothing about Raiden's new capabilities, but it's fun to argue for the sake of arguing.