I apologize for the intrusion but this discussion seems to be assuming that
Copenhagen and MWI are the only two quantum ontologies deserving any
thought. Granted, they are the most supported and seemingly sound ones but
that is more due to human convention and historical accident than to any
experimental or even theoretical datum (by the way, does Feynman's
sum-over-paths account as a fully fledged quantum ontology or just as
different paradigm to look at Copenhagen's?).
The one that I which to mention is the one supported by Roger Penrose for
his theories about the uncomputability of consciousness.
It is loosely defined but very attractive. According to it the wave function
collapses not when there's a "measurement" but when it affects a mass
greater than Planck-Wheeler's or rather when it has grown enough to have a
distinct effect on the continuum.
So, should you accept it, you'll need not to worry about defining observers and measurements or pondering on what multiple universes actually are. Wave function collapses are just another physical process with nothing particularly remarkable except the fundamental level at which it takes place.
The distinction of the quantum and classical realms has always been one of, in practice at least, sizes (though some quantum phenomena do take place at the meso-scale). So, what is most natural and logical than to place the barrier at a fundamental mass?
It is also, as opposed to other quantum ontologies, remarkably easy to experimentally test.
A consequence of this interpretation would be that if you could create a consciousness of sufficiently small mass (or rather, upload yourself to a support system with such characteristic) said consciousness would be able to experience the quantum realm at its fullest. What wonders would it see? Of course that said consciousness would contradict the theory that caused Penrose to propose this quantum ontology in the first place, but that's another issue.
Fábio Diales da Rocha