FA means there is an Atmos module built in the top. Not worth it in my opinion. The “ceiling bounce” does virtually nothing compared to a true Atmos setup with in-ceiling or height speakers.
The Reference Premiere is a step up from Reference, but truthfully if you’re used to Bose anything from Klipsch will sound significantly better.
I would budget $2,000 for all speakers and $500 for the receiver. It’s a great time to buy, Klipsch has some awesome sales going on right now.