I agree with all. I say this because of my current experience with both. I've shot the D loop and had to replace 3 because of wear. As cheap as it is to replace the loop it is bothersome. I currently have the U-N xl and love it. I haven't noticed any loss and check my Nok before and after every shooting session. There is no specified torque requirements posted for instalation so use discression. The precautions I have taken is that I have wrapped the mounting area with a 1.5 inch piece of silicone/rubber shrink, then mounted the U-Nxl using the supplied hardware. Over Kill maybe, but siding on the cautious never hurts. Most of you if not all have much more experience than me. I've asked questions and read posts from here and recieved great advise. I like what I currently have and have suggested it to friends. I've also informed them of what I have read here and the precautions I've taken. Just be smart and take in all info you read here and do what you feel is right for you and your set up. Hope it works out for ya. Happy Hunting.