It has no effect other then to make it smoother and more efficient. I started diving into the world of PWM chips recently but the vape they provide is extremely smooth compared to straight DC-DC convertors. PWM and PFM are related (pulse frequency modulation/Pulse width modulation) PFM is used in conjunction with DC-DC convertors to boost low end efficiency of the chips. Plus the G class features a buck/boost compared to most mods (for example the DNA250 chip) that use Buck only, which is inefficient at lower loads. What this does is allow a more smooth vape (and it shows on an o-scope as well) better efficiency (aka better battery life) and better low volt input performance (aka can fire higher watts with lower charged batteries) All in all, when hooked up to an o-scope the G class really shines in it's consistency, smoothness and performance, so whatever they did exactly, it worked right and justifies the price of the chip IMO.
The most important part of it, is the actual end user experience and in the end, the TC on this device is phenomenal. the watt mode is phenomenal. There is a noticeable difference in out quality of the output in both power mode and TC modes then most other mods, hence the "high end" label on them.