Well folks, I think I've figured out the answer to these comments by MikeC in his review of the Fortron Aurora: "The unpopulated portion of the printed circuit board by the capacitors is unusual, compared to the many other already seen that were OEM'ed by Fortron-Source. On most of those, there is no bare space on the board at all. Whether this lower PCB parts density means anything is not a question easily answered."
MikeC, I think there IS a simple answer, and I don't think it is unusual... I think it is a "feature" if you will of mass production. Basically, Fortron left that unpopulated space there because you reviewed a model that had NO PFC. Models that have passive PFC have a large choke coil in that empty space. A good example of a model with passive PFC and that choke coil is the Nexus NX-3500, which is clearly just a rebadged Fortron Aurora with that special Yate Loon fan.
Look carefully at these pics of the Fortron and the Nexus NX-3500 side-by-side (try to visualize the Nexus image flipped around), and you'll see what I mean. Notice that the layout of the heatsinks and circuitry is IDENTICAL apart from that PFC choke.
In fact, for fun, I even compared the results of Mike's testing on the two, and if you look at the charts, you'll notice that practically every single one of the figures is close to, if not dead-on identical!
Even the power factor measurements were similar: 0.62 - 0.71 for the Aurora, compared to 0.64 to 0.72 for the NX-3500. With these two units being almost identical, apart from one having PFC and the other having none, I'd say this is a PERFECT case study in PFC circuits. The verdict is clear: passive PFC clearly makes virtually no difference whatsoever. I'd say for all of you considering PFC in your choice of PSU: Go for active, or none at all. Passive PFC clearly doesn't make much difference (if any) and the choke coil is simply another HUGE potential source of coil noise.