No problem with mice. Years ago there was a rat in the neighborhood. There are people around with house cats that come out occasionally so I don’t think that between the domesticated cats there would be a problem with mice if the ferals were eliminated.
I ask because we had a feral cat “problem” at a place where I once worked. It was a large facility, about 16 acres, with lots of landscaping between the buildings. The powers that be decided to round up the cats and get rid of them. When they realized that we really had a rodent problem, and not a cat problem, they brought the cats back.