But of course, assigning weights to worlds in this way would be question-begging if you were trying to provide evidence for the Born rule itself.

You have completely missed my point. It's the difference between, on the one hand: proving that there is life on Earth, and on the other proving that if there is life in the universe, it must be on Earth.

Where TI would have said only one branch is real and the other branches do not exist, PTI says only one branch is actual and the others are real but not actual.

actual = the branch we're observing.

real = part of the wavefunction of the universe.

I maintain my position that it's the same thing as MWI.

To put it another way, as a proponent of the MWI you believe that there are real scientists out there, in other branches of the wave function, who perform their experiments with just as much care and diligence as you do and who end up with wholly different observed frequencies within their world. What makes you think you have the right frequencies and they don't?

Please clarify the question. Do you identify these scientists using the Born Rule to interpret the wavefunction so as to provide the basis for their consciousness, and making them just really unlucky in the outcomes? Because in that case, for every one of them, there are sixty gazillion jillion squillion ridiculillion others that get the same frequencies we get. This is very unlucky for them. Prospectively, we could expect their frequencies to fall in line immediately (and of course we can also expect that a vanishingly small measure of them will continue to fail to do so).

OR, are you finding these scientists out there in the wavefunction without using the Born Rule to interpret the wavefunction when identifying their consciousness, but using some other rule instead? If so, then the Born Rule isn't right for them.