So I got the extended warranty when I bought the boat. The main reason being is that after three years I could decide to dump the boat and make it look more attractive to perspective buyers if it had 3 years warranty left. If I keep the boat, well who knows until I get to the end of the warranty as if I will recoup the cost. End shot was that for 6 years, it is nothing but gas, maintenance and insurance.
You said brand new 2011. Does that mean you get 3 year warranty from time of purchase?
Waffle on the price of the warranty and they may come down a few hundred but most likely not more that that.
As to if it is worth it or not, it's sort of like gambling. You are not going to know that until it pans out. There is still a lot of electronics and other stuff to go wrong - ECM, master control module, guages, fuel pump, wiring harness issues, etc.
So you mentioned no wake plate on the X-15. I feel the wake plate is a necessity on the X-15 and would highly recommend getting it added.
I get my wakeboard gear from my dealer but then again they have prices that are competitive with the online shops. Plus they offer a guarantee that if you don't like the equipment that you get a 100% credit to a replacement. Use google, you will find plenty of online shops to price compare against.