Look at the fine print on the warranty. Lots of times you will find that very little is actually covered, like above covered the part but only if installed at the dealer price $$$$. I would pass on the warranty but I am very handy and can fix about anything myself.
Coach-Net is a good company, and my dealer threw in the first year coverage with them in my deal. Do understand that you can sign up with them without your dealer and I just did it again online in about 5 minutes after about 20 minutes of reading what was covered on certain options they had. The dealer might be getting you a better price, but maybe not.