I would recommend a warranty if you're buying a diesel powered coach, but not for a gasoline engine. I bought my 2010 Winnebago Journey in 2012 and bought a service plan from Cornerstone, 4 years, $4000. In May 2014, I had Freightliner in Gaffney go over it. In July 2014 on our way to Forest City, Ia, we broke down near Washington Courthouse, Oh. We got towed and spent 8 days in Columbus, Oh.
The bill came to around $20,000. Cornerstone paid $18,000, and I had to pay around $1,500. My deductible was only $500. But the shop made me pay the difference.
If you opt for the service contract, be sure to get Exclusionary and consequential damage coverage.