I have bought two trailers and one diesel MH and purchased the insurance on each one. I always by used and have so far received good value from the policy.
If I was buying new, I might hesitate to buy the warranty, especially on a trailer. Most of the components have new warranties on them and should provide you with a pretty good life cycles. In some cases, the big ticket items like the AC, Fridge, Heater, etc might have manufacture warranties that run out 2-3 years. The trailer manufacture's warranty should give you adequate time to discover any really large problems with the construction of the unit.
Other than that, pay carefull attention to what they DONT fix and who can fix and who can authorize work.
Dave and Anita
2015 Itasca Sunova 33C