In Joe Doe wrote:
You may choose to regard this as nonsense. However as I have pointed
out the opposite opinion to yours is actually held by numerous
gardening authorities (amend soil rather than replace soil). Clay is
good, holds nutrients, holds moisture. It only needs to be loosened
up for air and water and this can be done with amendments. Yes this
is slow but it is in fact preferred.

Joe, I live in a clay soil area. I've been using soil replacement for a
few years now, and the beneficial effects are a quantum leap ahead of
when I used to do soil amendment. No question in my mind.

Having dug up and replaced a couple of bushes, I always find that root
development (especially the small feeder roots) is far better in
replaced soil. The larger, thick roots tend to reach down and out in
order to strike the clay and that's a good thing too. Like you said,
clay is nutrient rich and it can be moisture rich too.

The other interesting thing is that, over time, clay particles do
migrate and mingle in to the rose mix. By then the roots have claimed
their domain (which would have been difficult if I planted in modified
clay).