I think doing these nouveau benchmarks of cards that can not be fully reclocked is a waste of time. The conclusion that you should not use nouveau if you care about performance just needs a quick look at the clock frequencies and no lengthy benchmark. The only benchmark that would perhaps be useful is a measurement of the power consumption when idle/ doing non-3D work (and comparison to nvidia driver).
The only good use case for the nouveau driver I can think of is for older cards (before all CPUs had internal graphics) when the PC is not used for gaming and you just need to get an image. And in this case you do not care about these benchmarks but about low power consumption.
If you have a high end or relatively new card, you normally use it either for GPGPU or gaming and therefore are using the nvidia driver and do not care if nouveau would give you half the performance or 10% of the performance.