Less welds means less weight. That's how they can call it a Mini 'Lite'.
As far as quality goes. My Northwood Fox Mountain had a fully welded booth dinette. We replaced it with a free standing dinette. I sold the whole booth setup to a guy that was rebuilding a camper. Obviously it was well constructed or no one would've wanted to buy it.
To top that, our bed support frame that lifts up is a fully welded aluminum structure. It also has plywood on it. Many you see are just plywood or worse yet OSB board.
Northwood's may not be all blingy but they are built solid. Show me another 27'10" 5th wheel with 4315lbs of CCC. You get what you pay for.