I remember when I was seeking quotes for a re-roof, one of the criteria I had was 'do you offer an insurance backed guarantee?' One or two said they offered a guarantee although not insurance backed, one or two didn't answer that part at all, and I think one said 'yes, however it'll cost you more.' It was really more of the cherry on the top for me i.e. not an absolute prerequisite to who I chose. I ended up going with an established local company, decent reviews, members of one or two pro bodies and listed on our council trusted trader.
Just out of interest, here's a broker who offer these guarantees to roofers, gives an idea how they're promoted to those in the industry. It would be interesting to know how many established decent roofers actually offer these.
Safeguard your project's continuity with our reliable and cost-effective Insurance Backed Guarantees (IBG) services, purpose-built for roofers and roofing contractors
cwginsurance.co.uk