I did something similar except used burlap.
I tried wilt stop on the figs, Some I didn’t spray, and they look worse than the one I sprayed. My figs in containers are all growing but all the in ground figs are still dormant (pass bark scraping test, green underneath) I think it will not work on everything. yet again though my blackberries pulled through with nothing but Wiltstop. No other protection. It was not that cold only once getting to -1F The boysenberries, and tayberries, pulled through fine. (both died to the ground 2 years ago, but have not since using protection) As Bob said though it is far from conclusive. Also it only lasts so long. You need to use it at the end of December for it to be effective January and February. Some swear by it. If dissication is the problem, and not just plain cold, it should work.
I think though that the thaw freeze cycle will kill anything. My blackberries are in shade all winter, and may be the reason they survived. never thawing out. Two years ago they were young plants. But I’m in zone 5b and boysenberries and tayberries are surviving outside. I have Newberry, Siskiyou, and Marionberry but they are in containers, and were in the garage. I had some dieback on them, strange. I’m getting no useful data here though. I put them out a month ago, and that could have caused the dieback. last year they started growing early so I kicked them out.
So many factors can cause dieback I can’t conclude anything. next year I’m just going to use leaves or straw.