Well as mentioned, there is no downside to making movement without a physics simulation.
What happens in the background is again just physics anyway 
It is something we call Kinematics. Which is describing motion without the use of forces which you don’t have to worry about it.
It is correct way of approach for arcade ship movement. You are using CharacterMovementComponent when you are making an Add Movement Input.
You don’t have to worry about physics (since you are asking without physics), I am a Physics Engineer, Physics is the father of all sciences. Every motion in the engine you see is physics either that way or this way. Even if we are talking on this forum with ease with you, its because a smart physicist invented transistor In short, this argument without phsyics is not a valid question. So let’s get over it cause Movement itself is the subject of physics.
Just wanted to say, don’t want to make a shortcut answer to your concerns. Let’s come to strafing stop issue you are having. Since you are using floating pawn movement (and if there is not other movement component interfering)
You should normally stop but maybe deceleration factor is low so you can increase it.