After 2015, they upgraded the frame to the STAR chassis and improvements and upgrades continued in other areas. Typically, the higher end coaches, like the L.A., get new gadgets and upgrades a couple of years before the Dutch Star. If you could find a 2018 L.A., I think that would be your best bet, especially the BIG motor and Allison 4000.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor