There is a huge amount of electronics in cars these days, especially true for hybrids. From bottom to top they are new kind of animal; from wheel sensors and regenerative braking modules to engine controls and monitoring systems, there is just a whole world of things to go wrong.
Conventional wisdom would say that if a Honda or Toyota lasts the 3 years of a typical warranty period then it will last 10, but it's a brave new world where a single sensor or labor diagnostics to trace a problem circuit can cost hundreds of dollars... do you want to take that chance?
On the other hand it can be a "pay me now or pay me later" and it may be cheapter to "pay later" - and who knows, in three years you may trade the vehicle in for a new hydrogen fuel cell jobbie or some such thing.
Perhaps you can get the extended warranty for half price if you make them think the deal is contingent upon it - and be sure to find out if the battery is covered.
Windshield treatment: Never tried the stuff but I have eaten more than a couple of winshields due to rocks - you'll be all right though, cause all the rocks and pebbles always gravitate toward my cars.
I don't know about the Honda Hybrid but we have tested some completely electric Toyota RAV4s and they have a special conductive windshield to repel the dust that electric vehicles may attract (it was a problem with the RAV4). Interestingly enough, if it got cracked from top to bottom the cars wouldn't run... if replaced with a standard glass they wouldn't run either.