I wonder what the point is at which you start to diminishing returns. I think Lance Hedrick touched on this in one of his videos but I can’t remember what grinder he was referring to :)
Because it makes me think, I seem to remember the role of thumb was to spend a certain % on your grinder, I seem to recall the advise was more on the grinder even, but my memory is awful!
I imagine that’s not a good rule anymore, you can buy machines that are easily 1-2k and then some, and it seems £700 on a grinder gets you something perfectly fine.