Reputation certainly won't go negative as a result of bag fees as long as they are reasonable fees. Especially if others are also charging fees. And I may still need to adjust the reputation affect if it's too strong. We'll see how it plays out.
Reputation effect is proportionate to how many passengers the fee affects (essentially which class(es) you have fees for). Having fees for economy will drop reputation gain by a bit, but having fees for business and first class won't drop it nearly as much because it affects less passengers. Unless, of course, your cabin layout and/or pricing dictates that you have more business/first class passengers than economy on board.
Another thing that I want to implement, that is not represented in route research, is that passengers will begin to carry less things with them if you start charging fees. So for example if you charge a checked bag fee, the higher the fee, the less passengers will actually have checked bags. Route research assumes all passengers have a carry-on and a checked bag.
Reputation effect is proportionate to how many passengers the fee affects (essentially which class(es) you have fees for). Having fees for economy will drop reputation gain by a bit, but having fees for business and first class won't drop it nearly as much because it affects less passengers. Unless, of course, your cabin layout and/or pricing dictates that you have more business/first class passengers than economy on board.
Another thing that I want to implement, that is not represented in route research, is that passengers will begin to carry less things with them if you start charging fees. So for example if you charge a checked bag fee, the higher the fee, the less passengers will actually have checked bags. Route research assumes all passengers have a carry-on and a checked bag.
I am the developer of Airline Enterprise