There is credible evidence that there are about as many nodes in the dark as there are in the light.
I'm not sure I understand what you mean. I've tried Tor and I2P and poked around a bit in the "pseudo-TLD" sites (.onion and .i2p). I didn't see much of i2p because everything seemed to be missing. As for Tor, it has some neat stuff going on but in a way it feels to me like a ghost town. Maybe I'm just getting a weird view on it. However, I wouldn't imagine that the dark net is the same size as the regular web.
Have I misunderstood what you were saying?