I had the opportunity to bring my hunter at the last minute to the weekly raid yesterday (it resets on Wednesday in Europe) and although I didn't take the time to configure Jamba for that character I had the good surprise to see that Lock'n Load was perfectly managed. The bar always was accurate and changed accordingly when the buff was prematurely removed. It helped me a lot to improve my dps I hadn't the presence of mind to take a screenshot though.

One thing i've noticed : If you try to change the size of the bar (in the settings screen) by directly typing a number in the field instead of moving the slider, that doesn't work. Not sure the intent was to have this field as feedback only or to allow to enter stuff directly there. I suppose the latter since the field is enterable.