Each individual should be free to decide for themself.
GAMI has done extensive testing on detonation, especially compared to 100LL.
GAMI’s long AML for engines includes the R-2800 engine used on many military airplanes and the DC-6B airliner. (It came in many power levels and design vintages.)
I understand that some people derate the engine to use lower octane fuel (with 100/130 hard to find and 130/145 perhaps near impossible).
Wikipedia quotes Lycoming as saying that special oil is needed with unleaded avgas, via an additive or some brands of oil, to properly lubricate the valve train.
Wikipedia notes other potential UL avgas offerings including Swift’s, but is mostly out of date on them. It refers to a new ASTM specification for unleaded Avgas (ASTM D7719).
Swift abandoned the STC path and went with the PAFI program, though its website is confusing. It has STC licenses on sale for $100 pr airfram-engine combination. But web stie is confusing between UL94 and 100UL.