I was never a proponent for extended coverage. We recently purchased a class A DP. My wife was very vocal about needing a extended service contract, just due to the many things that could go wrong. We purchased one in spite of my protests. It was around the $7000 price tag. To me it was a waste, as there is around 2 years on most appliances and chassis. The engine has a 5 year 100,000 mile warranty itself. And the warranty covers only five years. I can't believe I let her talk me into it, but I love her and she was part of the purchasing process as much as I was.
You already have a track record of finding out it wasn't worth it in the past. Being a older home I'm sure one will be up there in price. Bottom line is its a toss up. Put the money aside for repairs. Even if you have a big repair bill your savings fund might pay for it or take off some of the financial hurt. And you will collect the interest while it sits.