Isn't there a huge component of luck in staying anonymous? A needle can remain in a haystack for a long time without requiring any skill, either of it's own or of someone who hid or accidentally dropped it there. If time spent anonymous is "only remaining way to gauge how well someone hid", it's a pretty crummy one. I think it makes sense to take into account the kind of mistakes that brought someone out.

By the same token, we might just not have found Satoshi's stupid mistakes yet. Still, I think dobbsbob's point stands at least as weak evidence of Satoshi and DPR being different people.