I have seen countless expendable's hinge upon impact. Scary to say the least. I want my arrow to enter the body where I put the pin, and come out at same angle. I use wac'ems and slick tricks for years, and always been impressed with accuracy and penetration. With the big blades on the expandables now a days it doesn't take much for them to hinge when they hit. All it takes is a blade to not hit square and rotate the arrow. I have physically witnessed this. Got a wild hair years ago to try a rage my buddy gave me. Shot a doe at about a 60deg angle out of my stand. she was quartered away slightly with a hard downward angle. The arrow hit and hinged, and went through the deer perpendicular. I got lucky and still heart shot the deer. However it was enough to scare me from going back.
I know they work well for some people, but not me.