I used the "light pack, heavy pack" method with a mixed group of Scouts and Scouters last Saturday and it was great.
I packed two packs, one the way I packed five years ago, and one the way I pack now. They were equally prepared for a weekend. I didn't weigh them, but they light one was obviously lighter.
I had people try them on and explained that the two packs were equivalent in everything. The only change is choices between equivalent gear.
While people were trying on the packs, I explained that skills and planning don't weigh anything, but can save a lot when you choose gear. Fear is heavy, ignorance is heavy, "just in case" is heavy. I showed them my scale (the most important equipment), and talked about the method of weighing everything, lightening the heaviest items first, and the big three.
Then I had two people unpack the packs and lay everything out in two parallel lines. I didn't worry about matching up items.
Then we went through the items, picking one from one line and the matching item from the other line, and discussion the gear choice between them and the skills or planning that supported it. I also took questions about that kind of gear, e.g. down vs. synthetic. For example, the light pack had one fleece jacket, and I explained that I'd weighed them and this was my lightest mid-weight jacket. The heavy pack had my heaviest fleece jacket plus a PrimaLoft vest, just in case.
I talked about the packs last, so I could explain how smaller lighter gear meant a smaller lighter pack, and that more skill in packing allowed a less rigid (and lighter) pack design.
Finally, I strongly recommended Don Ladigan's "Lighten Up!" book.
All done in under 50 minutes, with plenty of time for questions.