Dynamic grouping is a nice feature, but when you have non-additive measures ( i.e. Level1 uses a different *column* than Level2 rather than summarizing Level2's column ) there's no way to display the different column based on the grouping choice.
There should be. Obviously the information is passed to the query engine at some point so the page can render correctly - that choice should be exposed as a parameter/variable for use in formula columns ( e.g. case($groupchoice = 'L1', C1, C2) )
Exposing that will make this nice feature much more powerful.
Note: I did raise this w/ support, just putting it out to the community to see if I can gin up some popular demand to bump it up the priority list 😉