One other thought: it may depend on how you use your RV.
> If you travel from RV park to RV park, then you are probably close to stores with repair parts - fewer spares probably necessary.
> If you typically "boondocK" like us, then you may not be close to a store for multiple days - more spare parts are likely a good idea.
So how you use your RV should be part of the equation IMHO.