I have the Fast Fire (so I guess that's a I not a II?).
It was easy to set. They give you a little wrench and it's the usual thing. Shoot a few, adjust, repeat.
Changing the batteries in the FFI is another story. I haven't had to do it yet and they claim 400 hours of battery life, so it will be a while. You have to remove the sight to replace the batteries, so you'll have to rezero then. Not sure if they corrected that problem with the FFII?
Btw, why would you get the FFII if you have a 1x capability in your scope if you don't mind me asking?