You’re still required to be negotiated for as a BUE, but FacReps don’t have to share info with you they get or any other guidance, nor go out of their way to assist you in other matters. You’ll have to go to management for that, as well as complaints or issues, whereas you could go to the FacRep as a union member, and they’ll fight your battle for you if it’s legitimate or get you some guidance from higher up in NATCA if needed.
At our facility, non-members aren’t allowed access to the Wi-Fi (unless someone gives them the password), technically the TV, or several other things around the facility the union has paid for. But there’s not enough of a non-union presence to cause problems or raise issue if the four or so guys who won’t be in the union get into those things.
And you can still wear what you want since you’re a BUE, but once again, if you show up in something management doesn’t like, not sure anyone will jump to defend your position.