In fact, I don't think our current rate of gaining new posters is sustainable. If you take out the first 4 or 5 most active posters, that start most of the threads, I think things would grind to a halt.
Most forums are constantly introducing new posters. Not all good(new posters-as we know),....but I think it adds interest that perpetuates and keeps a forum vibrant. And mostly you gain interesting people and their experiences.
But this is just my opinion. This is my favorite forum, too. I don't spend much time or effort on others.