Migrating to new (old) machine
 

I've used SuperDuper! to restore hard drives, but whenever I've migrated to a new machine, I've set it up from scratch. That's a lot of work.

I'm trying to figure out the most efficient way to migrate to a new machine such that I end up with the same operating environment as the current machine, with least post-migration setup work. And without screwing anything up (e.g. iCloud).

The SuperDuper! FAQ says don't do this, but gives as the reason the (valid) risk of cloning with an macOS version earlier than what the target machine supports. That shouldn't be an issue here, because (sadly) "new" iMacs are actually 2017 models, which originally (and still?) came with macOS 10.12.4 Sierra. Sierra is up to 10.12.6 now.

Resources:

• 2013 iMac with Fusion drive, Sierra 10.12.6
• New 2017 iMac with Fusion drive
• SuperDuper!
• Thunderbolt cable and adapter
• Gigabit Ethernet
• USB 3 external drive, containing SuperDuper! clone of old iMac

Would the following procedure work?

1. Boot up new iMac and create account with same name (and presumably UID) as the old iMac
2. If new iMac is running High Sierra, erase hard drive and install Sierra. Go to step 1.
3. Sign into iCloud (so that it can save the File Vault password in step 6).
4. Install latest Sierra combo update (so it installs any firmware updates), and
5. Install latest security update, for same reason
6. Turn on File Vault 2, let it complete encryption
7. Connect to new iMac in Thunderbolt Target Disk mode
8. Use SuperDuper to Smart Update clone from old iMac to new iMac

One alternative would be to do the clone before anything else. And/or, using the external drive as an intermediary: clone old iMac to drive, boot new iMac from that drive, clone from drive to new iMac.

Since the migration is Sierra to Sierra, and Fusion drive to Fusion drive, APFS shouldn't be a factor.

Since I've never tried this before, and so far haven't found hints for successful migration via clone, any advice would be appreciated.

Don't do that. Migrate from either a backup or from the original Mac over thunderbolt during first boot. See "I've got a new Mac..." in Help > Frequently Asked Questions...

But doesn't that assume that the new iMac comes with a macOS version that is same or newer than the source Mac?

For example, if the new iMac has Sierra 10.12.4, rumor is you can't use Setup Assistant to migrate from 10.12.6. And you can't update by logging in and running the App Store, because that would create a UID 501, and then you couldn't migrate the user account anymore.

In fact, even knowing what version of macOS the computer comes with isn't clear. Maybe start it in Recovery mode before doing anything else?

I'm wondering if the solution to the version problem is to erase the drive and install Sierra 10.12.6 (by booting from a Sierra install USB stick), then do the migration via Setup Assistant on the first boot.

I actually *think* it'll work with a close version.

You could update the OS (you can do this from network recovery, by holding down a certain set of keys during boot - Apple has a knowledge base article) but then migrate during first boot... that's definitely the way to go.