I think @TeknoJunky 's point was more about not all aspects of a transcode can be played off to the GPU; so even if you have more GPUs at hand, your CPU will be a limiting factor.
That being said… there’s already an existing suggestion similar to yours. I recommend you comment/vote in that thread in order to avoid distracting votes/attention.
In that case we should close this thread as a duplicate (sorry for the ping-pong).
