I'm relatively green on the Doomsday debate, but:

The non-intuitive form of SIA simply says that universes with many observers are more likely than those with few; the more intuitive formulation is that you should consider yourself as a random observer drawn from the space of possible observers (weighted according to the probability of that observer existing).

Isn't this inserting a hidden assumption about what kind of observers we're talking about? What definition of "observer" do you get to use, and why? In order to "observe", all that's necessary is that you form mutual information with another part of the universe, and conscious entities are a tiny sliver of this set in the observed universe. So the SIA already puts a low probability on the data.

I made a similar point before, but apparenlty there's a flaw in the logic somewhere.