Not much credit should be given to Waldi (IMO) because even if all the other top marathoners had been on a systematic doping program (The Sohs and Seko of Japan, and all the top Americans) their program could not have come close to the meticulously planned and financed one of the East Germans.
I am in no way suggesting that every top runner had a doping program, but Track and Field News voted Cierpi' the top marathoner of the century and defended their choice by saying that all the runners passed the same (ineffectual) tests during the 70's and Cierpi' passed those also. Therefore even though he was an exposed drug cheat... he was ... in their book ... no worse than any other top competitor in the marathon.
I have no opinion on drugs during that time (at least not one I will share with you), but when asked in 1980 how many runners on the U.S. road racing circuit were doped Frank Shorter and Rod Dixon said 30-40%. When asked how many were doped when you include blood doping they said 70-80%.
Anyway, if you read just a little about the East German sports machine you get a good feel for how they didn't hold back anything when it came to preparation and no holds were barred when it came to experimenting with PE drugs.
I have a hard time seeing how the other 2:09-11 guys of the era could have had as sophisticated a program going. This is not based on inside info though, just speculation.