They'll work fine (although with the normal expected slower writes of SMR drives) until a drive fails normally and the raid array has to rebuild (which is kind

They'll work fine (although with the normal expected slower writes of SMR drives) until a drive fails normally and the raid array has to rebuild (which is kind of the reason you use a raid array), then it could take a week+ and there's a very good chance you'll get more failures during and lose all your data.