> I think what most people want to know is whether they could re-write a multi-threaded program that is currently using synchronization primitives (locks, semaphores, mutexes, etc) with actors.

Really, it's not obvious? Of course you can: instead of shared memory you now have each actor having its own memory, instead of using locks and working on shared memory you now have messages and can ask actors to do something with their memory and send you the result back.