Sadly I don't see any benefits of implementing both in gameplay as well as effort to ensure its not an avenue for abuse.
Currently you can escape from an NPC or player encounter with 1% hull, visit a starport, pay money and voila you got your ship back.
Having a similar ship that is 2nd hand have an arbitrary setting that it can never be repaired to 85% efficiency doesn't make current sense.
what if I spend oodles on new modules, at what point would I ever get the ship to an equivalent level as a brand new one?
Why do I need to speed up ownership of a certain ship by buying a 2nd hand one at 85% or less of cost? For most ships the credits you need to buy it are just a toe dip in expenditure that you will lavish on it to get it to be a megamungous fighter/trader/explorer (delete as appropriate) ship.
Currently one of the powers gives 15% discount to ship purchases in their systems, that's a reasonable way of giving players more bang for their buck, as I see this doesn't do anything to enhance player experience or improve gameplay.
i would much rather FDev lavish coding time on the Vanity item of ship names, than spend time coding something like this.