Some users, as a matter of principle, never upgrade to a new major version of macOS until it is at least past its first update. Others are poised in the App Store on the day of release, and can’t wait to download and install it. Which should you be this year with macOS Catalina: an early adopter or cautious delayer?

The Catalina upgrade is going to be something of a heavyweight. It’s currently looking as if it will bring EFI firmware updates to all eligible models, something Apple managed to avoid with Mojave by bringing those updates forward into the last update to High Sierra. On top of that, Catalina brings major changes of its own. The most obvious is that all 32-bit software stops working the moment that you install the upgrade: Apple hasn’t relented and built in a ‘compatibility’ mode, so anything which uses 32-bit code won’t work.

Other changes in Catalina which are likely to cause significant problems for many users can’t be ignored. Its new read-only system volume means that software, scripts, or anything which uses paths to files which used to be in the /System folder (and some others, such as iCloud) could break suddenly. Apple has used ingenious means, including new ‘firmlinks’, to try to minimise disruption, but I know from my own apps that they don’t cover all the paths that can be used.

As Apple has already explained, Catalina also extends coverage of its privacy protection, to include locations such as your Documents, Desktop, Downloads and Trash folders, and services such as taking screenshots, recording the screen, and monitoring keystrokes. These might seem absurd to some, but aren’t actually as invasive as they sound. For example, all apps retain your ability to open and save files to those folders, to move items in and out of the Trash, and so on. What changes is that apps which want to do this without your explicit action need you to give approval.

So some of my apps which explore all the files and folders within a selected folder, looking for instance for old 32-bit code, will need your consent. The easy way to do this is – just as in Mojave – to give them Full Disk Access. In practice, that isn’t going to be a big change in the great majority of cases. Yes, Catalina can result in a flurry of consent dialogs, but once you’ve got your apps set up with the correct access, it really isn’t as bad as some have made oute.

Other security matters are, though, more irksome. When you install a new third-party kernel extension now, not only do you have to consent in the Security & Privacy pane, but before that extension can be used, you have to restart your Mac. As such installations normally happen when you’re installing software, to have to restart in the midst can be disruptive. Developers seem to be taking this in their stride, but it is something to watch for.

More surprisingly, Catalina is proving very pernickety over features we had taken for granted, such as System Preferences panes, LaunchAgents, and scripts run from other locations. I haven’t seen this affect a Preferences pane although others have reported it, but you may find strange odds and ends being dumped in a temporary folder, which is likely to prove puzzling. Those items moved in my case seem to have come from Apple’s own software, and not third-party products, but you will need to keep a watch.

These potential concerns in upgrading to Catalina aren’t likely to vanish, or even improve, with later updates, though. If you intend upgrading, you’re going to have to address them whenever you do eventually upgrade. So it’s more a matter of when you are ready to face them, rather than delay bringing any change. Indeed, if the Mojave cycle is anything to go by, the longer you delay upgrading to Catalina, the more stringent its security and privacy protections will have become.

Despite all these issues, there are still strong attractions in Catalina, particularly if you’ll be upgrading your devices to iOS 13 and want to use Sidecar, and want its new media apps to replace iTunes at last. It’s impossible to judge performance in betas, but in theory at least, dropping support for 32-bit apps should bring improved performance across the board.

There are several ways in which you could cope better with upgrading. These include retaining a bootable copy of Mojave on disk, and setting one up as a Virtual Machine (VM) in virtualisation software such as Parallels Desktop or VMware Fusion.

I normally run betas on an external SSD in a dual-boot system, and have done so throughout the Catalina beta period. The most significant potential problem in doing so arises if you want either version of macOS to make Time Machine backups of either or both systems. In the transition between Sierra and High Sierra, this was a particular problem as those two versions used different mechanisms for determining what should be backed up, and could trip over one another. There’s no reason to expect this to be a problem between Mojave and Catalina, but it remains something to be watchful for. I don’t use Time Machine to back up the Mac on which I run macOS betas.

Virtualisation is very attractive if there are only a few 32-bit apps to which you need to retain access. Having just set up two copies of Parallels Desktop, one on Catalina hosting a Mojave VM, the other hosting Mojave on Mojave, this is extremely straightforward provided that you have a copy of the version of macOS to be virtualised, sufficient disk space to accommodate around 30 GB or more for the app and VM, and a couple of hours to spare.

VMware and Parallels operate their product cycles asynchronously. Parallels Desktop has only recently been upgraded to version 15, which appears to run excellently in Catalina, although some trying to use VMware Fusion 11 (which was released last year) have reported problems. By the time of Catalina’s release, I’d expect both flagship virtualisation products to be fully compatible with macOS 10.15.

Upgrading to Catalina shouldn’t be daunting. I hope these notes help you decide whether to be an early adopter, or to watch and wait before making your move.