Do you have a forum credit/point system on your forum and do you think it helps to boost content? What sort of features do you offer with this system and do you have a shop included with your forum credit/point system.
We used to use a credit system on Christianity Haven, but we didn't have much to offer in the Shop to really make it worth paying each year for it. If you have items that can be bought with the credits then it's definitely going to be appealing.
I use them on a few of my sites however most don't bother to look or even use them anymore, shop items are very limited and I find having VIP sections is a waste of time, on a big board sometimes they work however keeping content viewable is the reason we all have sites.