RS6 is the beast you want for a wagon
We had a few 2021-2022 RS6s in inventory, and I swiped them for a few nights to "evaluate". Mrs. Hire loves wagons, so she did love the idea, but immediately after spending 3-4 days in one, we flew to Italy and had a diesel A4 Allroad as a rental for a couple weeks. Turns out, beyond the sheer flex factor of the RS6 (showing off acceleration to friends, and bombing on the highway), the Allroad did everything more agreeably.
The only reason we're getting an M5 is because she likes the idea of having an M5 Touring daily and an E39 M5 as her toy. And after specs and pricing are released, we may very well cancel on the whole idea and she just keeps cycling through annual Grand Cherokee demos.