Migrate SSD to another Mac...should I reinstall macOS? I have a customer who buys a 2012 iMac to replace his old 2010 iMac.  The 2010 iMac has an SSD with macOS 10.13 and would like to replace the mechanical HDD in the newer Mac with the SSD he's got in his 2010 iMac that he recently replaced. 

I have two options to tackle this:


I just migrate the SSD from the old iMac to the new iMac.  Then upgrade macOS from 10.13 to a newer macOS.  This will account for any driver incompatibilities as the hardware on the new mac is different.
I migrate the SSD likewise, but then reformat and reinstall a newer version of macOS, so as to avoid any driver incompatibilities.


Option 1 is certainly faster and will avoid having to reinstall apps etc.  Will I have major issues with driver compatibility, etc? 

Any help much appreciated.
MacOS is largely hardware-agnostic, in that every installation contains all the drivers for all the hardware that it supports. The only exception to that is special builds of the OS created for brand new hardware, released after the latest OS version.

I have physically swapped or cloned complete drives from one Mac to another for many years, across a range of different models, and OS versions, largely without incident.  

The only time cloning didn't worked for me was transferring to a Mac with a T2 chip, and yes, the issue (non-booting) was fixed by reinstalling the OS on top of the cloned data. I have not seen any other problems since then.

Migration Assistant is a lot better than it used to be, but is not without problems itself, (such as not migrating stuff), but if you want to go that way: copy the drive's contents to some other disk; erase and install the new OS; and then Migrate the data from the backup copy of the SSD's data.

FWIW, I have just migrated the contents of a 2012 MacBook Pro onto a brand new MBP, connecting the old hard drive directly with a SATA/USB cable, and it took about 8 hours for c. 600 GB of data.

It does seem broadly unnecessary to wipe the disk and then put everything back onto it!