Sludge, your statement that Beggs-Mueller works for the C152 is interesting as Beggs' articles only mention the C150 not the C152 and he reported that it did not work for some C150 spin modes.
Also, he only "tested" the 180 hp variant of the Decathlon and could not get it into an inverted flat spin. I wonder if that was because he was solo so had a fwd cg only - just my guess despite his comment that he "thoroughly tested" it. Still he does gaurantee the method, whatever that means. A 150 hp F/P Decathlon two up has a cg very much further aft.
PS - a bunch of Victorians will be trying to take the trophy next month.