The correct answer depends on your productivity software, peripherals and the OEM software for those peripherals. If it works, just install it on the main boot drive. But that could be true for any of the other systems as well, but at least you'd be current and good to go for a longer time. Odds are a lot of stuff will need work given where you currently are.

In your scenario I'd install Catalina on a clone of your system you can boot to, and test it. Having to download and upgrade new drivers, new software versions, fixing problems, reauthorizing apps, and just entering passwords is time out of work. The further you drop behind the more work it is to upgrade. In some scenarios and with some hardware that meant freezing systems, in others, upgrading every x months after the latest release. Over the decades I've found it helpful to have a strategy, instead of just making ad hoc upgrades when I had to. If I well understand, the HFS+ > APFS transition only affects the internal SSD system drive, but is smooth, transparent and with no problem ? And it does not change anything on the external drives, correct ? Still hesitating between Mojave (I'd gain a bit of time on the next fu*%+$.

I think I'll stay away from Catalina for now, leave it some time to maturate. It's my pro/production machine, but I'm a a casual user : Chrome, Thunderbird, Adobe suite CC, Carbon Copy Cloner, nothing exotic. Some external drives for photos, on thunderbolt 2, also : daily backups et backups of backups. System auto daily backup on external SSD (bootable yes, so turnback possible), MacPro 2013 (trashcan) 512Go SSD system, 64 Go RAM, Chances of such apps that will run on Mojave and Catalina are slim, like CaptureOne ver 10, won't run on Mojave and requires repurchase. It's just an educated guess on my part since OP mentioned he is on Sierra, so I'm guessing he is using apps that were prior to Sierra or bought on Sierra. But for lots of games and utilities, developers have not released 64-bit updates, and never will.Īgain this depends on what OP uses. The big ones, like Microsoft Office and Adobe Photoshop, sure. If money no object then Catalina, cos you can repurchase all the apps over again for compatibility.

I don't know what apps OP is using, might or might not have a fix for APFS. Many of the issues were with the new file system that Apple introduced, since the launch these issues particular are likely to have been fixed. I found something that mentioned some apps and at the bottom there's a short para:

Only OP can verify what apps he is using that is (not) affected by APFS. Hi.S can still be installed with HFS+, it has an option to run on HFS+ during install. How do you figure that? All three will convert internal SSDs to APFS during installation – but they still have no problem working with external HFS+ drives. If you have stuffs that still need HFS+ to run, then the only choice is Hi.S

How to upgrade from sierra to mojave