Be careful, I too thought they were the best thing since sliced bread. Several years back I along with four hunting pals switched to them thinking we had found the answer. Sure, if we had perfect hits (90% with no heavy bone on facing side) they did great. In fact most animals fell within sight of stand. However, if the shot was at an angle or struck heavy bone on way in, the animal was rarely recovered. This repeatedly happen to all of us. After two years and many deer unrecovered we have all returned to fixed blade heads. I probably know what your thinking, "but they fly so good," and "I haven't lost one yet." I was saying the same thing and now regret ever shooting those animals that we couldn't find.
P.S. Co-worker lost large buck yesterday. He said it was alittle forward but couldn't believe the arrow only went in 6-8 inches. You guessed it, mechanical head!!!