All great stuff ... but notwithstanding the science or art behind prop design all too often mixed tip designs were seen on the same a/c hanging on No 1, 2, 3 or 4 engines. Early strats are usually seen with round tips and later most BOAC used square but not exclusively. I thought it was probably a CE / HS difference but who knows.
As I mentioned even the Bristol Britannia Proteous engine is often seen sporting odd prop configs. on same airframe.