IMO, you are going to find happy and unhappy owners in every brand and type of rv. I would buy a floorplan that works for me within my price range.
Due to the fact that rv's use the same appliances,faucets, water pumps and pex pipes that weigh the same the 'lightweight' part of the build is the available materials on the market, to build the shell.
If you need to save weight, i would pick a floorplan with no slide and aluminum skin and pack it using cuben fiber backpacking equipment.
I say this because, if you took two brands of identical floorplans
'lightweight' and one that doesn't say 'lightweight' and put them on a scale to get a real weight opposed to a manufacturers claim, you might be surprised at what the scale reads .