It's just my opinion, but there definitely is difference in favor of optional static typing. It simply adds more expressivness to language - you get free documentation standard (input,output,structures) backed in. You don't have annoying typos and you leave data manipulation computation to computer lowering programmer cognitive load. Also you can change code in editor(fastest feedback loop) without even running it(very important if there is high price for running code - ex. complicated system bootstrap, deployment, hardware).

That, and also there are so many independent confounding factors in these comparison studies that I am not sure they can ever outperform reasoning or personal experience. The reasoning part in your comment - lowering cognitive load, faster feedback cycles (in editor, in compiler, etc.), fewer typo-induced problems - seems hard to argue with.

It seems both camps count lowering the cognitive load and faster feedback cycles to their advantage!

Good dynamic systems have long done live-coding against the running system with instant feedback. Even recent static languages like Rust and Scala have notoriously long compile times and thus slow feedback loops.

Also there's along tradition of querying the system for things like auto-completion / doc display.

The cognitive load of fancy type systems like Haskell's is seen as very high.