I don't have any idea what a weight reduction does to a bows resale value. A low weight bow might be easier to sell than one of a higher weight, but given two bows of the same weight, one original and one having been reduced to get there, I'm sure most would prefer the original.
In my mind, weight reductions are a great option for a bow that has some personal meaning, can't easily be replaced, or if the bow is in need of a refinishing anyway. But if it's just another bow, and is in good shape, from a dollars and cents standpoint selling the bow and buying another one is going to be the cheaper route.