Thank you all! Definately took a lot of worry away. I'll be giving it a shot tonight when I get home.
Just to help with the idea, I recently tested it for myself. I installed on a USB first. Got my SSD. I backed up the config just in case. I took out the USB and put in the SSD and did a fresh install. I did not load my config. To my delight, the pools were found and ready for use, data intact. The OS config does not obliterate your pools, that information is written to the pool drives themselves. You can take them out, put them back in on different SATA ports in a separate PC with a different FreeNAS installation and it will see that pool and be able to use it.
After you get your SSD installed and up and running, you can put a flash stick in and set it to mirror your SSD so that if anything changes, it's backed up to that flash stick while your SSD is your primary operating disc for the OS. Cheap downtime insurance. To do it, just go to System -> Boot -> you'll see your boot pool -> click the actions tab and select "boot pool status" and then you'll see the structure and disc name and status -> now select the 3 vertical dots on the far right and select "attach." This is where you choose your flash stick (or another SSD, whatever you want) and follow the prompts to have a mirrored boot pool for redundancy.
Periodically save your system config of course for not having to rebuild all your other stuff that takes way more time than simple pools, like your plugins, jails, reporting, etc.
Very best,
