Like I say my example above was a simplification, the engine will probably have a lot more things going on behind the scene when you apply a force, especially with regard to the objects mass, centre of gravity and inertia tensor.
You might be getting what appears to be the desired results at the minute due to no other forces acting upon the object but this will probably cause issues when other forces are thrown into the equation.
The only time you should really use an impulse is for a sudden instant change in an object’s velocity, i.e. an explosion, a collision which would see the object deflect off another or another surface, a player pawn jumping (technically you could do this using acceleration over the time it takes the animation of the pawn’s legs pushing up to finish but most games don’t bother).
I’ll try it myself when I get home using AddForce which should work.