I know the new "improved" plating method for trees calls for a saucer shaped hole with no soil amendment, but is this method recommended for j. maples? The Bloodgood is in a 15 gal container, has a 2 inch trunk, and is about 8 ft high by 6 ft wide. Some maple forums say to remove the all soil from the roots, open the root ball, and backfill with 100% native soil (no amendment) but I am quite intimidated to use this method on a $150 tree of this size.

We are at 4500 ft. elevation, USDA Zone 8a, and the new tree is still actively growing. It's still a few weeks until frost here. Our soil is very fine, almost powdery texture with little organic material. It drains well. Native cedars, pines, and variety of small oaks species thrive in it. It is fine but not clay. A "Crimson Queen" maple planted last year is doing well near the spot for the new tree. Questions:
1. Is the "remove soil from roots" method appropriate for a tree of this size?
2. The tree is still leafed and active. Should I plant now or wait until the leaves drop?
3. Should I backfill with no organic amendment even in our low-organic soil?
4. Should I mix in water-holding polymer beads (e.g. "Soil Moist") as insurance against soil drying out?