I do agree that a lot depends upon the type of pond, and the skill of the builder. We have both types of ponds, primary pipe/emergency overflow, and simply a primary, earthen overflow. From what I have observed over the years, I wouldn't hesitate to skip the pipe and go with the earthen overflow. Provided it was built the way I directed, and the geography suited it.

"Forget pounds and ounces, I'm figuring displacement!"

If we accept that: MBG(+)FGSF(=)HBG(F1)
And we surmise that: BG(>)HBG(F1) while GSF(<)HBG(F1)
Would it hold true that: HBG(F1)(+)AM500(x)q.d.(=)1.5lbGRWT?
PB answer: It depends.