For any insurance plan you buy, you are actually making a wager with the company. You are betting them that you WILL have a claim before they make their money back and they are betting that you WON'T have a claim before they make their money back. Like any casino in Vegas.....they payout much less than they take your money. Not saying that we don't need insurance plans and/or warranty plans, but just saying what they are.
I say take the bet against yourself and invest the money you would spend on premiums for extended warranties. That way if you don't have a claim, you are making the money yourself (interest or dividends)and if you DO have a claim, well, you have saved the money to pay for it.
To me, it's kind of like using the federal income tax refund as a savings plan. I hear of many people that are soooo happy that they will be getting a refund, and in fact they withhold more of their paycheck each month to ensure that they get a refund at the end of the year. Not sure why that's a good thing since what you're doing is letting the government use your money interest free.