We use a Chroma loader and test harness to assess the quality of the PSU. What we really want to see is how much better the Pure Power 9 is than genuinely budget PSU from well-known manufacturers. The recently-reviewed System Power 8, priced at just £45, will make for an interesting comparison.
The trio of supplies do just fine when loading the 12V line. be quiet!'s Pure Power 9 is the best of the bunch, but it would be impossible to tell in day-to-day running.
Cross-loads are harder for a PSU to deal with because voltage is being concurrently applied to different rails at one time. Think of it as loading up your CPU, graphics and peripherals all in one go - a worst-case scenario.
Cross-load 1 puts almost all of the capacity down the throat of the minor lines while stressing the 12V line(s) with a couple of amps. The reverse is true of cross-load 2.
The Pure Power 9 maintains the slimmest of leads.