I have no experience with anything other than a parallel-to-the-ground front end on any rifle, tactical or otherwise, and (campaign medals notwithstanding) none at all in a kinetic situation, and frankly, that thing looks weird.
I can see definite benefits for myself, but not on every single weapon I own. With my carpal tunnel syndrome, it positions my left hand into a more comfortable position. It also lets me curl my hand onto different angles so as to provide some relief from having my hand forced into a certain position for an extended period of time. I tried vertical handgrips, which provided some relief, for a while, but these angled ones work better for me.
Oddly enough, the Magpul handguard with its odd curved/triangular shape, seems to work well just as-is. If I find problems later on, I'll probably go with an angled grip again.