I've read that the weight relief thing has been going on for years, maybe late 90's. And with the newer ones apparently they're all done. Check Harmony Central. I saw a big thread on this somewhere, just can't recall where. I think what pissed people off about this was that Gibson didn't make it common knowledge. People found out about it on their own and started asking questions, and Gibson started with the excuses.
Here's one quote from Gibson on HC
"The weight relief pattern has changed for 2007. We have modified the original Swiss cheese hole pattern to something that has a purpose other than to lighten up the guitar. Originally, the holes were cut in a pattern that maximized the available space and did not take into consideration tone, balance, and sustain. So, we felt that a scientific approach was best if we were to change the pattern. We knew that we could now measure frequency output of the guitar and also determine positive or negative effects of any changes to the internal routing. So, we initially approached the project from the perspective of just improving the placement of the original holes. As we began testing, we noticed that when we moved the holes closer together, sound and sustain improved. We then decided to try moving the holes so close together that they actually created one big hole instead of several small ones. The area volume was the same but the improvement of sustain and output was greater. This drove us to start playing with the actual shape and size of a single large chamber and then to multiple chambers, strategically placed inside the guitar. We couldn’t do much with the control pockets and pickup pockets so we decided to focus on all of the mass and area around those routings. After several months of testing, the current sonic tuning pattern emerged. This pattern works in all Les Pauls and gives us a much better sounding instrument, sustain is improved, and as an added benefit, weight has been reduced by 20%-30%. Sustain can be improved two ways; by creating rigidity and by sound reverberation. While reducing weight further wasn’t our goal, it definitely should be received as a positive side affect to our real goal; giving reason to our original weight relief pattern of holes.
Regards,
Roger Ball
Gibson Customer Service
service@gibson.com "