All-Red (and High-Crit) Builds and Fox's Prayer
Let's say one's going for a build with as much weapon damage as possible. Typically this would also include around 60% CHC and high CHD, though not always. (Using the Pestilence LMG is one example where 5% non-crit weapon damage is preferable even to 12% CHD, since crit damage doesn't apply towards Pestilence's debuff.)
Assuming you've got max or near-max attributes for all kneepads, under what circumstances in such a build would you not want to use Fox's Prayer kneepads? These provide +8% damage to targets out of cover, which is a separate multiplier I believe, and so even if you're not using a rifle still worth more than the additive +10% weapon damage buff you'd get from another brand specific to your weapon.
In other words, can I get rid of all my weapon-damage-enhancing kneepads except for Fox's Prayer?