and to the question for 40 to 60 size sport planes I use whatever I have on hand mostly plastic not going to spend 50$ on a 2 stroke 46 powered sport plane .
for my warbirds and larger 4st engines alum is the safest type of spinner of course, and that is what I use .
the debate who is cheapest buys the cheap spinner bunch of B.S. is what that is.
I am far from cheap and have several thousand $$ in planes, engines, and radio gear, and I can guarantee there is plenty of plastic in there and they work just as well as the alum. ones at a fraction of the price ,spend your $$ where you want it has nothing to do with taste and everything with bad attitude about the cone your plane has on its nose and how much you spent on it, just start that thing and fly eventually your gonna crash unless your just putin around