What strikes me the most is that all the Les Pauls in the 8-9 lbs range are always LP Standards.
It seems much, much harder to find a weight relieved LP Custom that weighs in this range. I've played and owned countless Les Pauls and I'm a believer that the 8-9 lbs range is most perfect, above all in tone; open, lively and dynamic with lots of balls and shiteee loads of sustain. As a LP purist, I think it's the trick to find a great piece of wood in the 8-9 lbs range. Too light in weight = bad. Too heavy in weight = bad. Bad wood = bad, no matter the weight. I'm mainly talking about the influence of weight on the tonal balance and characteristics of a Les Paul (assuming you're having a good piece of wood).