Your reputation rating will rise or fall depending on the quality of the posts you make. It's - supposedly - not a popularity contest, and as everyone gets over the "newness" of this system, I believe things will shake themselves out, the cream should rise to the top, the chaff... well, you know.
In the meantime, as you've already noticed, the Reds Live forum has the same functionality as the Reds Talk, or "Big Show," forum does, so there's no reason that you can't enjoy yourseves here.
A hint: I believe the new system was instituted to cut down on the number of "this player sucks" threads. Not that there's anything inherently wrong with "this player sucks," but it's better received if you have something to back your opinion up with... and no, "he's fat" isn't a good reason.
Just talk baseball, have a good time, stay away from grinding axes and getting into member vs. member squabbles, and you'll find yourself with full forum access.
Act petulant, and you'll find yourself staying here. Not that it's a bad place to be, but realize that not everybody wants to see eighteen different threads on why Rich Aurilia walks like a duck or somesuch when they log in in the morning.