If you're just using the ZW as power for the Legacy system I would just keep it, as long as it meets your needs. My ZW will handle an ABBA set of F3s (dual Pullmor motors) and 6 aluminum passenger cars on one track and an ABBA set of F3s (dual Pullmor motors) with 9 scale refrigerator cars and a caboose on the other track no problem. The case gets a bit warm after about an hour to an hour and a half of running but that's it.
Put some inline fuses or breakers between the track and the ZW and you're good to go.