FWIW I use a 3 ring and medium pressure regulator and will boil the ass off a keggle.. I also have a over the side imersion element if I want to get to boil in a hurry, usually not though...
I have a Mongolian burner welded into my brew bench run on a high pressure reg. Dont know why you'd need anything else, boils a 100 l stainless kettle in no time and I don't ever have it on full bore. I love it.