Burden of proof IS the whole point of a debate, and there can be none because the final PS4 is not out yet.
This requirement is not made in the hundred of threads discussing other hardware/software. For instance, it is not made in threads discussing Haswell performance gain over IB, despite Haswell "is not out yet"
No one is arguing that PS4 will not be more efficient than a PC. What is not yet clear is how much the added efficiency of the PS4 will require in PC hardware to make the performance equal.
From my part I have always emphasized that I am working with estimations, not with final numbers. When I say 5x I don't care if it is finally 4.6x or 6.2x, because it is only some average estimation.
And speculative statements from developers with a vested interest in the hardware do not count.
Are you trying to say that the words of recognized developers have to be taken less seriously than the words of anonymous forum posters, with unknown identities and interests?
Moroever, I already cited a developer from the competence (Nvidia), who said essentially the same than the developers that you consider "with a vested interest in the hardware".
But, and this is
the point, some of us are discussing the hardware and the technical details, not a mere "X said so".
I started to quote developers
only when people asked for sources for some of the technical claims made, such as the existence of API overheads.
I continued citing developers
when someone said that the they were said something different about the PS4, which was untrue as shown.