In Susan H. Simko wrote:
I'm of the "dig a big hole in
the clay, throw away the clay, and fill the hole with good soil" camp.

I'm in the tent right next to yours :-)

When I shovel pruned a couple of roses last season, I dug up one where I
used the native soil and one that had the soil replaced with a high
quality rose mix. The difference in root systems was remarkable - over
50%. The rose with replaced soil had grown and bloomed far better too.
It was hard for me to believe that I'd planted both as bare roots, at
the same time.