Eli - As you said in an earlier post, it is not the testability part of MWI that poses a problem for most people with a scientific viewpoint, it is the fact that MWI came after Collapse. So the core part of the scientific method - testability/falsifiability - gives no more weight to Collapse than to MWI.

As to the "Bayesian vs. Science" question (which is really a "Metaphysics vs. Science" question), I'll go with Science every time. The scientific method has trounced logical argument time and time again.

Even if there turns out to be cases where the "logical" answer to a problem is correct, who cares if it does not make any predictions? If it is not testable, than it also follows you can't do anything useful with it, like cure cancer, or make better heroin.