Correlation between weight and "quality" build

Our 24' no slide KZ was an entry level unit and weighed about 4500 lbs. Our 28' with slide Keystone Bullet weighs about 5,200 lbs. The 24 had a full steel frame and aluminum siding. The 28 has partial lightweight frame and fiberglass siding.

Prorated, the 28 is much lighter per foot of unit, yet seems that the quality of its features are a little higher. I've only owned it almost 2 years, so time will tell.