I recently tried them, and they are a great light gpi arrow. After watching videos showing little difference in penetration of heavy slow arrows compared to light fast arrows, I've changed to light fast arrows to gain the trajectory advantage.
I can assure you that a heavy arrow will penetrate quite a bit more than a light arrow when they are otherwise set up the same and shot from the same bow. My focus is on large bull elk. With that in mind, I consider "very light" to be 450 or lower. I consider "very heavy" for NA non-dangerous game to be over 600. Lots of space in between those limits for "kind of light" and "kind of heavy".
I'm getting a LOT older and am reviewing my arrow weights and I intend to drop my weights a little bit because my draw length has somehow slipped from a solid 29.0" to something a bit less, and I've lost some strength. so, I "get it" in terms of the search for lighter arrows.
Not sure what "videos" you've been watching, but IMO most arrow penetration YouTube videos are less than worthless (less than zero because of the cost associated with the time was spent watching them). Just my opinion based on my own direct experience. Sure, there are probably some good ones out there.
Plus, there is that thing called Physics.
I'm not saying that light arrows don't have their place. I too grapple constantly with the advantages of flatter trajectory vs. the ultimate goal of making sure that the arrow does its job under a range of outcomes. I also understand that some folks have shorter draw lengths or cannot pull higher poundage and sometimes that tilts the scale towards lighter arrows despite the risks of limited penetration.
However, it seems like too often when I follow the tantalizing siren song of light arrows something goes wrong and I don't get an exit wound on the elk.