Im not saying how great it is. Im just saying it looks great to me. I haven't used one. Charlotte has bigger trees than Detroit, and I am guessing bigger canopies than the Pacific North west. Scotty runs a crane all day everyday. I only run a crane once every few months and one of my crane guys makes me use his shitty slings (with no clevises).
If done correctly those shackles are stronger than the rope itself is. It is far superior than a knot. There is, from what I understand centuries of use behind this configuration in situations with pretty serious consequences if there is failure. So I think there is a lot of historical knowledge on this technique that we have to work with. Both of us should be pretty good at inspecting and monitoring the health of rope. Yes maybe there might be abrasion issues, but people do chock slings without clevises all the time. But maybe like JOMO said they are hard for grounds to undo or they will get tangled up in the canopy. They also won't smack you in the teeth. Are you worried that the piece would fall out? That it wouldn't choke or the knot would pass throughout the eye? It seems equally likely that someone doesn't tighten the clevis screw properly as set the knot properly. Both require a bit of focus and awareness.
Above all else, Im going to try my best not to get into an argument
Ive been doing crane work since I was 20. Im 44 now. Never had anything fail, never dropped a clevis or been struck by one. I might be a little rusty at the moment, but Id still bet my craning skills against anyone out there. Not to sound boastful, but I'm just confident about my abilities in that particular field.
So, I made some points earlier, but Id just like to give you a quick example. The job in the pics happened maybe 6-7 years ago. I took down that tree with 4 cuts, and good slinging....especially the first 2. We had to stop 4 lanes of traffic to the first 2 cuts....the second lift needed to be especially precise, because it partly hung down below the wires. Couldn't afford any rolling or twisting. Lot of activity on the ground as you can imagine, but as I recall the whole thing was pretty seamless, and we were away before lunch or there abouts. That Blue sling has a 6 T WLL, the clevis is similar or more from memory. So, as well as adding an unknown quantity into the equation, invalidating our insurance, contravening the safety standards for crane lifts....what, if anything would we have gained by the inclusion of that sling we discussing ? Nothing, is the answer.
Perhaps if we took the tree, or a tree down one branch at a time, we might make some gains. But as is, I see nothing remotely tempting me to use one.