Last Week on My Mac: Would you regret an M1 iMac?

With M1 iMacs selling as fast as Apple can promise them, it’s time to take stock on where these first Apple Silicon Macs stand. Are they really ready yet for any Mac user to switch to, or would you regret making that choice?

I have no doubt that a great many who purchase an M1 model now will be over the moon with it. They probably won’t even notice which apps use Rosetta 2, although those running native will usually deliver noticeable performance improvements. Provided that they don’t rely on Boot Camp or running Windows in a Virtual Machine, most of what people do with their Macs just gets better. And if they should need features like Recovery Mode, they’ll be even more impressed with the thorough job Apple has done.

There are voices of dissent, though. Some, such as those needing more memory options, should be addressed when Apple delivers Apple Silicon Macs aimed at the higher end of the market. I have to keep reminding myself that, just because my M1 Macs perform as well as my iMac Pro, it doesn’t mean they could replace it.


One apparent limitation with the Fabric of the M1 SoC (which replaces I/O components in Intel chipsets) is that it only appears able to support two Thunderbolt ports. Although Apple has had ample opportunity to offer an M1 model with four Thunderbolt ports, in the case of the more expensive M1 iMac which does sport four USB-C sockets, only two of them offer Thunderbolt. For M1 laptop users, this hurts even more, as one of those two will be occupied some of the time by the charging cable.

Many M1 users are therefore relying on docks to provide traditional ports such as Ethernet, and the other connections they need for external disks and peripherals. Currently, compatibility with docks is an uncomfortable area, with some M1 users reporting serious problems including consistent kernel panics when waking from sleep with certain models of dock connected. It’s unconscionable for a laptop user to have to stop their M1 Mac from going to sleep in order to use a dock.

Security, NVRAM and boot disks

M1 Macs have a complicated security model, quite different from that enforced by the T2 chip, which is difficult enough at times. Although this allows an M1 Mac to boot from an external disk without changing its security settings (in the way that you have to with a T2), recognition and use of external storage for such purposes is continuing to trip M1 users up, particularly when combined with relatively immature Big Sur installers. In recent versions of macOS 11 this hasn’t improved as much as it needs, and now even the NVRAM seems to have become locked down from the system.

Users who never try booting from an external disk are unlikely to notice anything amiss, apart from the fact that changing the startup sound setting in the Sound pane no longer works properly on an M1 Mac. External SSDs used to extend the Home folder or to store backups work fine.

Try connecting a USB-C SSD to a Thunderbolt port, though, and chances are that you’ll be unsuccessful installing macOS on it, and if you succeed, you’re very unlikely to be able to update it through Software Update. To get most USB-C SSDs to boot properly from an M1 Mac, the solution is to connect them via USB-A when installing or updating macOS. At least, that’s what seems to work in macOS 11.3. This doesn’t require the disk to remain connected to USB-A, though: once macOS has been installed or updated, the disk can be connected to USB-C again if you wish.

Prior to 11.3, Thunderbolt SSDs appeared the more reliable, but after I spent days performing mindbending testing, I think the balance has now swung in favour of cheaper SATA devices connected by USB-A. Attempts to update macOS on a bootable Thunderbolt SSD now seem to fail more often than not, and the only workaround is to install the full release of the updated macOS – another serious shortcoming of M1 models at present.

Two M1 Macs, one boot disk

Macs, even those with T2 chips, have always offered the user choices as to how they’re used. Although the most popular is to boot each Mac you use into your account on its internal storage, many prefer to go around with their own bootable system on an external disk. This is ideal for someone who wants the same environment, apps and documents when they’re in the office as when they’re at home.

The good news is that’s now possible using M1 Macs, with some significant cautions in addition to the current limitations over updating bootable Thunderbolt disks.

You probably don’t want to try this with just any M1 Mac, though. Getting your wandering drive to work with a new M1 Mac is quite a fiddle, and not something you’d want to do every time you go into the office. With just two or three different Macs, it appears quite usable within the limitations now imposed by macOS.

Assuming you’ve already set this up at home, and arrive from work with your bootable SSD in your bag, to boot your Mac from that disk, you then have to do the following:

  • enter your normal user password to log on;
  • enter the password for the internal SSD;
  • enter your Apple ID password;
  • complete 2FA to verify access to your iCloud account, using a six-digit code.

That’s a far cry from simply logging on, although none of those steps is peculiar to M1 models, nor are they even confined to Big Sur.

Developers and multi-boot systems

A few users, particularly developers, need to be able to boot their M1 Macs into several different versions of macOS, for example for testing their product in each of several releases. This used to be relatively easy to set up, adding volumes to the boot volume on their Mac’s internal storage, or with multiple systems installed on an external bootable disk.

Although some have managed to pull this feat with an M1 Mac, it isn’t straightforward whichever way you try. Hopefully Apple will address this before developers start trying to install and test betas of macOS 12 through the coming summer.

Are M1 Macs ready?

Yes, but you should still tread warily if you need:

  • more than 16 GB memory;
  • more than two Thunderbolt ports, or to use a dock;
  • to boot from an external disk;
  • to boot more than one Mac from the same external disk.

It looks like there will continue to be long queues on the M1.