I agree with most of that, but I don't understand why you think DTrace is less invasive than another filesystem. They could have shipped ZFS all along and only now declared it stable, if they wanted to. They also could have integrated it again, now that it's actually more portable than before due to OpenZFS. I don't use Macs, so I don't have a direct interest in ZFSonMac, but using a filesystem which can be accessed from Linux, illumos and FreeBSD has some practical aspects which are definitely missing with APFS. Someone will eventually, unless Apple prevents it with IP and Patents, implement APFS for BSD or Linux, but just as NTFS-3G, it will never be fully stable and reliable as a Mac version of OpenZFS could have been. Apple's own APFS implementation will be stable of course, and for other versions to be good as well, they would have to open source the critical bits.