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?
Yes, I was referring to the number of persistent bitcoin nodes on TOR versus the number of persistent number of nodes visable on the open Internet. If you have the skills, you could set up a bitcoin client to
only connect to other nodes via TOR. I wouldn't be surprised to discover that there is a .onion address for a major online wallet service, or a wallet service entirely within TOR.