I have been a caver for almost 30 years. I've made my own harnesses and gear and trusted my life to it many, many times. I have no problem with making my own jacklines and tethers. As already pointed out, just use the proper gear for attachments.
"When in command, command." -- Admiral Nimitz
Difference between a power boater and a sailor out on the water: A power boater is going some place special, a sailor is already there.
s/v Zotz 1981 Pearson 365 Ketch Hull #375