Agreed, back-lit would have lesser number of LEDs, but it still does not explain the straight 50% weight reduction. Weight of individual LED is hardly anything to make much of an overall weight reduction. Could be something else ..... maybe, the light guides used in the edge-lit ones could bring about the increase in weight.
BTW, checked with a Sony service engineer .... the LEDs are placed only on one edge, and not all round the edges. The light guides do the guidance! He was'nt able to come up with anything on the weight difference though.
Watching '3 Idiots' on Sony Max just now .... superb picture quality. The panel too is not an issue ... colour mis-match only happens at extreme wide angle viewing ... such angles never happen at my room. Overall, very pleased with this purchase with the hope nothing untoward happens in future.
Thanks to FM aks316 ......