I have used them the last two years and killed two elk. First one totally lived up to billing: passed through (three bones): the shoulder blade, rib, chest, another rib and lodged under the skin on the far side with 85% retention. This year the bullet went through the big bone just above the elbow (very large bone) shattered it and the bullet did come apart, but one big chunk went through the heart and she went down in short order.
I have had good accuracy and good terminal performance on the two elk I have taken (both cows) and would not hesitate to use them again. However, I have 2 boxes of 300 gr Thor bullets ordered. If they fly well, I may use them for elk next time. A solid copper Barnes bullet of 300 gr with a reliable expansion and solid rear core just seems to be about the best you can do for an elk.