All that aside, I really don't see how you can tell the quality of a SMPS based on wieght, maybe I'm missing something here?
It isn't a foolproof measure by any means, but more weight generally means larger heatsinks on internal components, larger transformers/inductors, and bigger capacitors, all of which can help improve longevity.
It used to be all but fool proof, but the newer high efficiency designs are proving difficult to measure by mass alone. Sometimes it is necessary to peer through the vents. I now looks for some distinguishing features of a good PSU:
Decent finish and thickness of the enclosure but overly flashy may be a sign of trouble.
Fan type (ball bearing, magnetic or hydrodynamic are best)
Wire size (no 20AWG wires except for sensor or control leads)
Board material, better PSUs use fiberglass PCBs, cheap ones use phenolic.
Component brand choices, especially on capacitors!
Heatsink size is not a huge factor with some modern designs with efficiency ratings over 80%, small can sometimes be OK.
The last tell tale sign: warranty
Wit that said, even a quality modern 80+ efficiency model will still have some beef to compared to the cheap crap.
