Power 15 warranty for 458 Spider

My 458 Spider warranty provided by the dealership runs out shortly and I am looking for views on what to do for the future. The car is 11 years old and has done 12,000 miles and will do about 2500 miles per year. Power15 is about £3700 in addition to the annual service for an Annual 2 service …. An expensive year.
I would welcome any thoughts as to whether to go ahead with the Power15 or not ?

I run mine without a warranty.

I have a good Specialist.