The academics will have you believe these Rope Wrench static pull tests are crap.
They say the same about the break tests Treetools does but we believe this style of testing is better than nothing - it's certainly better than proprietary data secreted away in some corporate vault (that none of us mere mortals are privvy to see).
Below are a couple of graphs taken directly from the treebing video. Note the 'smoothing' effect of the Rope Wrench in the bottom graph.
The top graph replicates our own friction hitch testing - Treetools has not witnessed the test bed 'smoothing' effect seen in the bottom graph but it does correlate with emerging anecdotal evidence regarding the behavior of the Rope Wrench in the work environment.