The SKX are very inefficient when it comes to auto winding
If you have a sedentary job you might not fully wind the watch when worn (I have had this issue when sat in my office all day)
Are you sure the power reserve is reduced? It should be around 42 hours when fully wound.
With regard to value, yes it has a value but if there is an issue I would say the value is market rate minus the cost of a service - so not much.