I voted for No since I think that 50posts are a bit to much. There could be a higher post requirement though. Thinking more of 30-40 at highest, and even 40 seems to bit at the highest side. Since this also is a forum mainly about tracker invites, maybe create a bit more side content around it, not to much, or trying to raise the quality of it somehow a bit more? =)

I also don't know the exact requirements for the rest of the topics but maybe also mainly change that?
Give Invites: 10/15 [Asking 15-20-25]
Competetion: 15+
Trade/request: 25+ [ Don't know which of those should be higher. Trade as possible place to scam, request as of rudeness for asking for invite while not even connected to community?]

Hope this helps.

Edit: Oow you could throw in the requirement right away, don't see that make any difference. Only of people changing there opinion at highest since they are suddenly the subject.

Greetings, Elonoir. ^^