Question to everyone, "Is there any advantage to having the "heavy" lid on the Kettle vs. using foil?
The MSR kettle lid is kind of unique in that it has a tight fit compared to other pots. You can probably use this pot without a stuff sack and keep everything in place. Of course, a stuff sack is still going to be lighter than the lid, so it's not really a weight advantage.
You can pour water without removing the lid, so it might be slightly safer.
You can also drain water (like when cooking pasta) a bit easier with the heavier lid vs a foil lid.