"Don't convert your production startup disk to APFS this fall."

His full blog article is here.

Waddya think? Indeed, this gives me pause.

As one of the people who just wants to "do stuff" with his Mac, and not dick around under the hood, I don't think I'll be checking the APFS box this Fall.

Mike Bombich has stated it is going to take a LOT of engineering work on his part to handle the additional partitions on the High Sierra boot drive on HFS+. I am confident the virtual partitions on a APFS volume are going to cause him to burn even more gallons of midnight oil to figure out how to deal with them. I respect Mike Bombich, his talent, and his products but his opinion in this case is not unbiased.

The old saying is, "Fools rush in where angels fear to tread" so I guess that makes me a fool and you can take what I have to say with that grain of salt. As expected I am encountering some challenges with High Sierra Public beta 1. However I am encountering zero issues with APFS. In fact I am enjoying not only a measurable, but a noticeable improvement in disk I/O on both SSD and Spinning Rust drives. (The spinning rust improvement was completely unexpected.) The only downside is one that I have been expecting since the initial announcement of APFS, is the impact on third party utilities.

I had not thought of the issues with previously mentioned issues with cloning utilities, but I had long expected the volume repair utilities Diskwarrior, Drive Genius, and TechTool Pro to be in a difficult situation with APFS. Their various hardware tests are still valid, but many (most?) of their maintenance and repair functions are inadvisable on SSDs and APFS makes them not just inadvisable but counter productive on both SSDs and spinning rust. Where do they go from here and what are they going to do to justify their $100 price?

On the other hand there have been multiple discussions on these forums about how necessary are these utilities in today's environment. I can't remember the last time I launched TechTool Pro or Drive Genius to optimize the file and/or volume structure much less to make repairs. I know it has been multiple years. I very occasionally use TTP to perform a full check of the SMART parameters of a drive but now the freeware Etrecheck does that too. So the utility developers have to convince me they have something I need or want to justify their price.

I don't "do" betas, but am most interested to see the release version...

According to Mike Bombich's recent Blog:

"CCC 4 will be qualified on macOS High Sierra, but the majority of our APFS compatibility support is going into CCC 5. CCC 5 currently offers bootable system backups from APFS to APFS, HFS to APFS, and APFS to HFS. Additionally, APFS encryption is supported for both source and destination APFS volumes, as well as for remote Mac source and destination volumes. You read that correctly – CCC 5 can automatically unlock and mount your APFS-encrypted volumes on a remote Macintosh, and do so while maintaining the security of your encryption key in a keychain."