Keep in mind that fluidised be reactors already operate at scale...

Keep in mind that fluidised be reactors already operate at scale in similar applications, the CDP was sized just large enough such that if it works, it provides strong evidence that it will work at much larger scale.

Also note that energy loss due to radiation, which a plasma process would be significantly effected by is proportional to the temperature to the power of 4 ie. T⁴. So if you double the temperature of the process then the radiated energy loss is 2⁴ = 16 times greater. Of course the reactor is insulated for both processes, but the higher internal temperature inevitably leads to higher energy losses through leakage or in the hydrogen / graphite that leaves the reactor at high temperatures.

Another issue is that as the reactor gets larger the surface are to volume ratio is also not linear, with surface area following a squared function, and volume a cubed function, so the larger it gets the more volume proportional to surface area, and so the lower the heat losses per unit volume. I think the fluidised bed reactors can be increased in size, but this may not be the case for plasma reactors.

I remember somewhere the Hazer chief scientist saying that the hazer process loves to be scaled.

So on the basis of that, my money is on the Hazer process - literally.