I think I'll just run whatever comes with the iMac on the internal 256 Gb and use an old 256 Gb SSD I've got in a caddy connected by USB-C or USB-C 3.1. I presume I'll be able to boot from such an external drive?
Macs have been bootable via USB since Apple switched to Intel chips.
The new Great Equalizer is the SEND button.
In Memory of Harv: Those who can make you believe absurdities can make you commit atrocities. ~Voltaire
