OP asked:
"So some of you have recommended external enclosures for SATAs and others portable SSD drives. What are the main pros/cons for these types of setups?"
Well, the advantage of "pre-packaged" is you just take it out of the package, plug it in, and use it.
But be careful -- sometimes pre-packaged drives come with factory-installed software that can "muck things up" with the Mac OS. It's better to REMOVE this software first, and then ERASE the drive using Disk Utility before you begin using it.
The advantage of buying an enclosure and a "bare drive", and then assembling it yourself, is -- YOU put it together, so you know what's inside, and YOU can take it back apart again if you ever need to. I usually do this myself.
The cost "is a wash" either way.
I have one of the Oyen Digital enclosures, and it's built like a tank.
Goes together easily with only a few screws.
Highly recommended if that's the way you decide to go.
Either way, I think you'll do fine.