To take a stab at it and expose my line of thinking. All this assumes a well tillered bow.
I believer the fades and inner limb are what give you your string tension. They are the stiffer part and set the angle for tje limbs. I believe anything you do to the inner limbs affacts the torque of of the bow and as a direct result and perhaps redundantly stated, early draw weight. Because early draw weight is so directly affected by the inner limbs Id say that is where your string tension comes from.
I believe the tips produce your horsepower, as they are the faster moving parts. They determine more of your final end of the fd curve as that part of it is what is affected so much bu being whip tillered or stiff levers or recurves. So id wager that reflex in the tips will increase your hp ( speed ) of the bow, but in trying to carry on with the car analogy, I wonder if that decreases your torque offerings of the inner limb? Would midlimb be the mid range of this machine and be perhaps the best place to reflex a bow?
In an effort to gather my thoughts, I am typing so forgive my rambling.