XigmaNAS

I have a spare 500 GB SSD kicking around and a couple of extra SATA ports on my NAS4Free machine. At "only" 8 GB, memory is a bit tight. So I'm thinking I should migrate swap to the SSD.

And maybe some non-critical directories? The most likely candidate would be /var. This would allow log files to persist across boots.

The system is primarily used for archival storage and backing up other computers. I have Finch installed and will be running a low-traffic Subversion server behind Apache httpd in a jail, and maybe Transmission in another jail.

So what makes sense to move to SSD?

is your swap being used at all?

or put the whole embedded or full N4F on the SSD

Swap hasn't been touched yet. But I haven't really been working this server at all.

I'm not sure I want to do a full install. Sure, it would boot faster, and free up a modest amount of RAM. What is the upgrade process like when a new release comes out?

You can also install the embedded version to the SSD.

What is the upgrade process like when a new release comes out?

On full you need to boot from the LivecD/USB and upgrade the system from there.
Embedded upgrade can be done with webgui.

Embedded runs the OS from RAM
Full runs the OS from the boot drive.

except for the on die cache, the RAM connection is the fastest in the computer
thus embedded operating systems are way faster [all else being equal]

the embedded on a SSD will boot faster than USB flash
but this is not of much interest [mine last booted 55 days ago]

swap on a SSD will be faster than swap on a HDD, but way slower than more RAM