I was thinking about it and I have an idea. What if the merits were treated like a currency? So quality posts earn merits that have real value. The market can have a limit to how many you can buy per day based on your rank. Say 1%/day max merits you can buy. This will stop people from quickly buying a whole bunch of merits and ranking up so to make sure it is an active member only 1% of your max merits can be bought. That means if people want to abuse the system they will have to stay active anyway for 100days so it is not really worth it for them.
In fact, I think since the high value of sMerits (not Merits), which users can send to each other. Those sMerits will be traded in "Black Market" under shadow, out of the forum. I hate to say that is bad or good, because it totally depends on approach of each user. It might be good if users have positive approach, and vice versa if users have negative approach.
Nevertheless, in general I think merit system will help to build up the forum faster, make it better. Let's think positive, it will change the forum and change your accounts