I have owned a Summit Goliath for about 4 years now and I would say that damage to the tree is a definate concern. I can easily see where and what trees I have climbed after just once up and down. In fact that is what I look for if I am unsure in the dark. Does it kill the tree?? Not to my knowledge.......but I could be wrong because it would take many years for a good size tree to completely die and fall over.

This is especially true if you climb a smoother bark tree and also when I get to my end point I give both top and bottom a little "rocking" back and forth with some weight on them for a little extra "dig" and security. I am solid as a rock up there but it surely DOES damage the trees. I don't "rock" or do anything special on the way up or down and the marks are very clearly seen.

My buddy has an older API Grand Slam with a serrated V blade on it and that thing absolutely mangles trees!! He has a tree he likes to climb and it looks like a flock of woodpeckers hits one side of the tree every day all year.

I would be very cautious if you think they may freak about tree damage. Some people have different definitions of what they consider "damage"