I never said your character was overpowered, in fact I believed from the start it wasn't really equipped to deal with the Mech which is why I offered the Clockwork Man instead. What I do think is overpowered is the ability to sense absolutely everything an opponent is doing with the only limitation being ranges exceeding what you'd expect T5/6's to be able to conceivably attack at. Not only do I think that power is overpowered however, but it's also completely contrary to what you said your character could do. It uses echolocation to detect enemies, which is a perfectly acceptable substitute for sight and also far more useful in many fashions, such as being able to see an enemy behind you or in the dark while running away. It's limitation scientifically is that it relies on sound, which is slow. It was not the optimum method for avoiding the bullet, in fact it was not even a possible method for avoiding the bullet. 

It has just occurred to me that I may have a serious OCD that Arena triggers, but the moment something happens that seems contrary to what is physically possible I must question it. 

Regardless, your character does have its air pressure ability, which is obviously used for avoiding projectiles. Using that would be completely fine but -not- in the fashion you're describing, sensing the movement of the rifle (if it were, why would the Pater have echolocation at all, when the air method is far more overpowered). It's up to you whether you believe your character could avoid the bullet upon sensing it with its air pressure ability, it's not up to you to bend the rules of physics and have sound move faster than the rifle round.

Ultimately, with your character now invisible to the only remaining method Higan has of spotting it, the only way this fight -can- conceivably continue is for your character to be winged by the round. At which point Higan can pursue its blood with his Computer Sytems. Hell, it might even be able to turn it to its advantage. (With the computers I admit to taking liberties with, though only for the sake of necessity as you had made your character completely un-trackable and miles away, story wise Higan would not wander the woods for days, that would be insane and pointless.)