Those times I have seen a direct comparison, where both regs are working as they should, the AMP seems to have less pressure drop from a full fill, and down to regpressure. While huma may have 4-5 bar drop, the AMP may have 2-3. In those cases the AMP should in theory be better, but it would probably not make a practical difference. Think allot of the "huma is better than FX reg" come from the older models of impact, and FX guns like wildcat mk1, and the royale, where huma reg probably is a better option. On the old style regs, the huma is much easier to adjust, making it a better option for a tuner.