Mixed feelings.
I understand the intent and can't argue with the model you're suggesting. Afterall, it is your forum. Stanley mentioned $25 or $5... it doesn't matter. I think he makes a valid point in that charging ANY fee should keep away the pure garbage. Let's just hope you go with $5 instead of $25!
On the other hand, I think you could accomplish the same without a paid subscription model. Basically, you have to earn your stars and stripes. The "premium area" would start with whoever you deem "worthy" - mods, guides, whoever. Within the members area there could be a forum called "initiation" whereby:
Thread Title = Members Name
Poll = Accepted or Denied
Outcome = certain % wins acceptance with a minimum number of votes needed
Let the existing "premium members" decide who is worthy of the "inner circle". You'll basically need people to "vouch" for you... ie eliminating the bullshit. If a newb wants to "get in" then perhaps they can pay their way in but at the same time, what is to stop Google or Facebook or anyone from ante-ing up $200/year to get the lowdown on the showdown... the "dirt" so to speak?
There are positives/negatives no matter what you do so obviously you have to do what's in your best interest. I'm just offering a few ideas off the top of my head after reading your thread.
Goodluck with whatever you choose... I'm sure it will make WF an even better place either way.
Cheers.