These have been discussed quite a bit on Sailing Anarchy.
Ferrules such as those from Antal and Schaefer make a lot more sense as they are stronger, ligther and if they fail the failsafe is still in the eye splice.
The Shockblock is cool but is limited to a very light load applications which there aren't to many of on our boats. And there is no failsafe if it breaks unlike a ferrule.
If you want the easiest way to test loads, spinlock makes a load cell for measuring road loads.
https://www.spinlock.co.uk/en/load-analysis/zs-ropesense-2/10-tonne-wireless-load-cellI've used it, nothing super fancy but easy to use. I'd love to try it on the F18 one of these days.
... $4,500? I would rather have a set of sails.
