I follow your thought process on resale value. There are so many variables in the resale side it is not easy to answer. The 5th will cost more up front than the BP and therefore usually draw a larger return in the end. How the vehicle is stored and what the original price was compared to increased pricing in the future has a major element in the value.
With that thought I don't believe proportionately you will see a large difference. For your resale value maintaining the unit will provide a better resale than any thing else to worry about.
