To buff the agi builds, the time window for chamber could be a little bit prolonged and the time to block a chamber a little bit reduced, so the str builds get chambered more and can block less: should make less str spamming, waiting for double hit, better possibility for the agi builds to chamber.
And regarding chambering not as block and attack but deflect and attack, the chance of an attacke to crushthrough while being chambered could be reduced or completely removed. Successful deflecting the energy: no hit. Kind of using the enemy force like in Aikido.
After rereading my post, seems that I like the double hits somehow :-)