We bought a 5yr/60k mile "service contract" on the Bounder just before the original 3/36 powertrain warranty from Ford expired.
Never had to use it for the powertrain. That 2nd generation 310hp V-10 has been flawless in 36K plus miles, and I just had it checked by a mechanic friend using his scan tool during a 40 mile trip back to the house, and every parameter was well within norms.
As for the service contract, it did replace the cooling coil on the fridge, one of the leveling jacks, a roof air and the AC/DC Converter. About $3500 worth of repair bills for the initial contract cost of $1500, and about $600 in deductibles.
Service contract expired in early 2013, and all the quotes for an annual contract were around $1200, so for the past 2+ years I've been saving my money and covering repair cost out of pocket.
To date have only had a main slide gear fail, which cost $750 to repair, but I know as the Bounder gets older, more things will break, and I just have to reason with myself over $1200+ annual cost of a service contract, or keeping that $1200 and covering repairs out of pocket.
I'm sure a major system failure/$4-5K repair will have me second guessing myself.