It has a huge red flashy light letting you know you are outta paint?? Rather have that than a massive whirring next to my face ;DI have 2 rotors, Z2 and the new Spire.
The Spire is good and having put 2 boxes of paint through it, I think its pretty good. Frenchy said its quiet which I agree which can be a problem.....firing away and before you know it you run out of paint but think "why am I not shooting". With the rotor you hear the loader when its empty
I guess its something to get use to. I'd rank it Spire, Rotor and Z2 last