I’ve used one off and on for the past three seasons. I started using one mainly for bears since their ample fat and long hair can result in poor blood trails at times.
I found the 30 pound test to be very durable, but so heavy that it affected arrow flight. The 17 pound test does not seem to affect the flight of my arrows, but it is also more susceptible to breaking.
Over the past three seasons, I have shot one bear, and one deer with the string attached. The string broke on my bear, but that was the result of me using a very fast crossbow, which I think was just too fast for that string. The friction Created by those speeds was too much for it, and I believe it broke in the flight.
I have a bear hunting buddy, who has used one for years, and absolutely swears by it. He shot a bear a few weeks ago. His shot was a little back and he hit liver. He followed 300 yards of string before bumping the bear out of its bed after dark he went back the next morning and met a guy with a Tracking Dog and they found the bear across the highway about 100 yards from where he bumped it. I Purchased, my string, spools and canister from TurkeyHuntingSecrets.Com.