jezbrews
Apprentice commercial brewer, amateur home brewer
From what I can tell, with (the majority of, at least) all-in-ones you still need a separate hot water tank and FV, so it's just mash to boil, which is only a part of the process. I'm not trying to be simplistic or flippant here, I'm just confused as to what makes something like the grainfather "all-in-one" with an eye watering price tag and you still need other equipment? I feel the only difference in process from a three tier is that you mash and boil in the same space, but that's it.