We're comparing the Fractal 500W to a couple of other SFX-L supplies that have a higher wattage threshold.
Voltage regulation has never been a problem for any modern supply, even ones that are relatively tiny on the outside. Cross-load is where it can hurt the most, when you put little load on one line and lots on the other(s). Even so, in a worst-case scenario, our Chroma test harness shows the important 12V line dip to only 11.85V. No reason to be concerned with these results.