My 2c worth ...
We previously owned a KZ Durango 1500 275 and we were very satisfied.
Some things to consider about lite weight units:
I) insulation value is low as the walls are thinner
II) lite framing i.e. around doors, windows etc. vs. a studded (house like) framing (can't remember the technical name)
III) Cupboards tend to be lower to the ground and not as deep as to not put too much strain on the walls
IV) Appliances tend to be smaller i.e. check the size of the oven, fridge size
V) Basement tends to be smaller, with smaller access doors (my pet peeve)
VI) Holding tanks & water heater tends to be smaller capacity
VII) Frames tend to be lighter in construction, could be subject to cracking or twisting depending on application
VIII) Less and shallower slide outs
IX) Typically will support only one pre-wired AC unit.
You also have lots on the plus side, typically lower to the ground and lower height creating less wind resistance, more economical pricing etc.
Bottom line, it is all a matter of preference and your intended use/application.
We loved our KZ but upgraded as part of our retirement plan.
Good luck. Enjoy !!!!
GPG52