I would ask you :
Whats your annual mileage?
What issues have you had to date with the car?
Wat is the cost of likely component failure - ie gearboxes, turbos etc are normally good. So that leaves modules like GP, SAM, etc which are common failure points i think but only £100-250 to replace. So in one year they would all need to fail to cover the cst of the warranty?
Presumably the Tier1 doesnt cover consumables, discs, pads, tyres, non standard fluid changes?
What is the value to you for peace of mind?
I personally would never touch extended warranties from third parties, worthless! But main dealer like for like - seems expensive but depends on preference i guess.
Just my tuppence worth.