Which is why all the WC downhiller’s are riding an air can…not. Look, a coil, especially a Ti coil, with a properly designed leverage rate will always out perform an air can. Why? 3 reasons: 1. progressivity: with the exception of variable volume air cans (DT had one of these), air cans always ramp up making it difficult to balance small bump compliance with bottom out; it usually hurts when you need it most…eg. big drops; 2. stiction: seal friction makes the shock less active and slows the changes in shock direction (this is not tunable damping and changes as the seal ages); 3. Heat: seals and compressing air generates heat. The heat affects the damping circuits.
With a Ti Spring= almost no weight penalty. Few manufacturers are designing plush air can bikes. To achieve near coil performance, you would need a falling rate with a spike upward at the end (air cans lack substantial bottom out bumpers).
If descending is your thing, buy a Ti coil and be happy!