I wasn't aware that adding a new controller would work.
When Reboot made the point to stay in the 128gb or under that's what I did. I'm still curious if OWC was just hustling me (not likely from all I've heard) or if that was really an option.
I might have popped for the controller just to have the extra real estate but they did not reply until AFTER I ordered the Seagate.

Still curious if I was being hustled!