I think that the value of purchasing an extended warranty depends on at least 2 factors.
1.) how many miles to you plan to ride in the warranty period? Is there enough risk to offset the price of the warrant?
2.) Do you plan on keeping the bike for the duration of the extended warranty? If you buy the extended warranty and sell the bike before the warranty runs out, you probably will not get much resale value on the warranty.
Remember, that the warranty company is counting on the gamble that you will sell your bike or not ride it enough to have significant warranty issues to make a profit.
But the peace of mind of having a warranty is sure nice! I'm thinking of extending my warranty as the factory warranty gets closer to the expiration date.
Also, don't be afraid of negotiating the price of the warranty. Most dealers will deal on the price.