I would say no. The fact of the matter is that warranties are big money makers, and statistically speaking that manufacturers are making product so good nowadays (to minimize returns) that the warranties aren't really needed.
Also, if you are buying a $300 head unit, by next year it might be $250, and 2 years from now it might be $200. So you get a $200 head unit (when you will probably want the latest and greatest).
Warranties are big money makers, and are basically insurance policies. Typically you insure stuff you can't live without (car, house, belongings inside the house, significant other's income, etc.)
With technology the way it is, do you really see yourself wanting to have that radio in 2 years?
I bet you will get a few people who say "I bought the warranty and used it". But for the most part if you posted "How many bought a warranty and never used it" you would get a ton more of replies.
Juan