well my friend I hope you can do this !!
member should create x topics to be able to reply again to other topics ( x topics admin's manual choose for this special group and for individual member )
admin can put group or x member in this advanced group ( no need to be default group) only the permission should be added to current group
member can be auto move after x reply or manual move to this group ( exception for admin mod and donator group... )
after moving to special group ! when he clicks reply .. he will see a message!! you are not allowed to reply until you create x topics
if limit is 5 reply.. so after creating x topic ( already choosen by admin ) .. then the count of reply restart again
so example : each 10 replys need to create x topic
just some info !!! you can change what I wrote to get better config for ext
THANKS