As I said above, requiring merit to post in the regular boards almost certainly won't happen as theymos is against those sorts of restrictions.
@DdmrDdmr suggested somewhere to introduce a Merit-based sorting for new threads. I don't remember what thread it was but I think that will be a good alternative. The sorting should be based on how many merited users responded to a thread.
Also, Loyce's Comment comes to my mind on Spam Filter v1's thread. Something Like a "Reading" Mode should be introduced, Once in the reading mode, all the posts made by users who haven't received any merit will not be shown. I mean it's not required. The Bitcoin discussion board is much more readable these days can't say the same about Altcoin boards tho. The topics are usually crap or don't belong in the bitcoin discussion board. I think adding a moderator or 2 should help the cause.