At my organization we have provisioned many cross platform file shares for various use cases. We have one group which copies files from their PCs out to a share and then they process the files from several RHEL servers. We typically set the security style to NTFS due to its granularity however it depends on the users. I would advise against using a mixed security style as it would cause more problems than it solves. Is there any reason why you could not use a UNIX or NTFS security style on a cross platform file share?