boathouse boatlift problem

I have a z520 ranger and my cradle that picks boat up and down is rusted up and in bad shape. I have talked to boat lift warehouse and they offer wide nylon straps rated for 12.000 pounds to lift and lower boat. has anybody used this product and if so give me your opinion. also the people that sell the straps told me I had to get approval from my boat manufacturer to use the straps. having trouble getting ranger on phone to get an answer. what would be the concern for using straps.