General Section Based on posts.
my suggestion is open up a second general for people with 1k or 1.5k posts and above. while keeping the regular one open to both.

That is quite a good idea, since it´ll reduce the spam Threads for the ´real´ users. On the other hand, General is for everyone so make it like this:
General #1: Open to everyone, everyone can post.
General #2: Open to everyone, 1K+ may post.