That sees your quick-chat on X, your Enter Guard Mode on Left Bumper and your Guard Break/Execute on Left Trigger.
My reasoning is, entering and exiting guard mode is circumstantial, reactionary. Where as a counter-guard break needs to happen INSTANTLY. Resting my Left finger on L trigger, ready for a counter guard-break is far more comfortable and efficient than moving my finger to the Left Bumper as it is set in one of the already existing layouts. Please and thank you very much if you do.
Might just be the way I hold a controller. Thoughts?