I agree that spam should be kept to a minimum, but I like the idea of rewards for posting based on length and/or content as opposed to just "posts" - replying with a +1 isn't the same as having a real answer.
Personally I'm not a fan of any rep systems, but I know that a lot of people dig them so I won't complain.
Maybe in future there could be custom titles like "Grand Quester" or "Moneybags" or something (less lame) to denote users that are number 1 in some area?