Davex,
i also plan to hold on to my car for 10+ years. my dealer offered a buyback on the extended warranty. at the end of 7 years if nothing breaks, i get its cost back. i figure if anything does break after the covered 4 years, it will at least cost the price of the warranty. also, you may want to choose to act quickly. the contract may be prorated for milage.
i hope this info is relevant to you. i purchased my IS from a Hawaii Lexus dealer.
good luck on your choice.