The truth is that we don't know.
First, both assumptions may be false.
For example, "many worlds" is over simplification of the Everett's theory. In the last one only Schrodinger function exists, and it is complex, not real, which prevent us from numerical calculating of the number of the worlds and observers. Quantum anthropic becomes difficult. I am now reading an article on the topic, and hope to understand it better. http://arxiv.org/pdf/1405.7577v3.pdf "Self-Locating Uncertainty and the Origin of Probability in Everettian Quantum Mechanics".
Number 2 will result in catastrophic consequences for my future. Because I have only one normal next moment - there I will continue to write this comment, and thousands on unpleasant next moments, there something disruptive will happen with me, most of them will be different catastrophic events - a plane would hit my house, and so on.
I think that different way of calculating measure should be used, where measure is proportional to the energy of calculations. This idea imply existence of minimal "plank observer", and all other observers are interoperated as number parallely running plank observers. This number could help to distinguish between measure of existence of different copies of me, if they are running on different computers.
It does not solve your problem unfortunately, because here we have two completely different types of carriers.
I agree with criticism for 2 assumption. Although I have this intuition (based on possibly very wrong intuitions I have about QM), that argument still works even without it: Imagine same human runs the simulation. Then he goes to another table where he runs spin measuring experiment, with 50/50 probability of getting either up or down. After seeing the result, there is now two different consciousness of him, but there is still just one copy of simulated brains as they did not saw the result.
Lets assume few things:
1. Many Worlds is real.
2. All identical consciousnesses measures as 1 in anthropics . So if we have set of consciousness: 1xA,1xB and 1000000xC, it is still 1/3 chance, to perceive being C.
Now say some intelligent being (i.e. human) starts another human brain simulation on silicon chip. The operations it does are all discrete, so despite the chip splitting in to many chips in many worlds, the simulated consciousness itself remain just 1 (because of #2 assumption).
But that is not true for human who started the simulation as he differs somehow in every Everett branch and reaches billions different consciousnesses really fast.
Is there some mistake in reasoning, that real persons should heavily outweigh simulations, despite, how many of them are running, given such assumptions?