I never take extended warranties out on anything. The way I was taught, more years ago than I like to remember, is that any insurance/warranty is a gambling proposition with the odds stacked in favor of the insurer or warrantor; they wouldn't be in business if it weren't (just like casino gambling).
That being said, I'm also good mechanically and can fix virtually anything or replace the parts myself if they aren't repairable. If, on the other hand, you aren't good at diagnosing, repairing or replacing (my father, may he rest in peace, couldn't change a light bulb without trouble), then the peace of mind offered by those plans may work for you...just keep in mind, they are in business for themselves, they are not in business to take care of your needs. Many loopholes in most plans; make sure you read the small print and then weigh your odds based on your own abilities.
My 2 cents, your mileage may vary...
2 Cats; J-Lo and Ragamuffin :R
2014 Thor Tuscany 40RX DP
2011 Ram 2500 Longhorn CTD HO
2011 Keystone Cougar 318SAB (now gone)
2008 FunFinder X 210WBS (Sadly gone)