Weight definitely affects tone, but most people now believe the old 70's idea that a heavier guitar always sounds better than a lighter one is just a myth.
Roger Sadowsky is a boutique builder of Fender-clone-ish guitars and basses, and he started routing chambers under the figured tops of his higher-end bodies to save weight, and found that they actually sound better than the un-chambered ones - more resonant, more lively.
Purely anecdotal on my part, but my 13 lb bass is very even and controlled in tone and volume... it really sounds and feels like I'm running through a heavy compressor.
My #1 is about 5 lbs + a few ounces and has better tone than any other guitar I've owned.
It's the Gestalt and has always been the Gestalt. I'm more of the opinion that some cuts of the same log are more musical than others and when you combine that with matching the proper wood characteristics to the requirement of the player you've got magic!
Weight does not equal tone. There are a million factors and variables that will effect tone. Check out anyone who plays a 4 pound parker fly
Here Adrian goes through variation of many tones.
My #1 guitar is a 10 pound warren haynes 58 les paul but if I play it for 3 or 4 hours with the band one night the next night you will probably see me with my parker fly or else I am probably sitting down! that guitar can kill a guys back, especially at my age. That being said, I dont let back pain get in the way of tone.
I wouldn't think in terms of better and worse but in differences. I've got a 78 Les Paul that weighs a ton and sounds fantastic and an alder body PRS that's light as a feather in comparison and sounds fantastic. Different but one's different tan the other. Find the sound you like and go with it.
thanks. I've fallen in love with a Les Paul. I've heard a few musicians exclaim their excitement in how light their axe is, and I initially pinned on it the idea that they are on their feet with it strapped over their shoulder for three hours, so the discomfort of a heavier instrument. My thoughts definitely went to resonance when I heard its possible weight may affect tone, and I've always been fond of trees so my weirder side went to the soulfulness of certain wood with soundwaves vibrating through and off it. Favorite tone to date in a touring act is by far Trey Anastasio's hollow Languedoc.