Bombproof vs. Weight for remote, unsupported gravel centuries
I'm looking at doing a few unsupported gravel centuries this summer, Almanzo and Woodchipper in MN, and Gold Rush in SD. All of these are unsupported and from what I understand can get pretty remote. The Woodchipper in particular is a smaller event in an area notorious for spotty cell phone reception. This is only my second year gravel grinding (I actually started late last summer) and I'm using my old steel hybrid Trek 700.
My question is one of tires. Last year I used Schwalbe Smart Sams 700 x 40 on my Plan B trail bike, aka The Goat, and later swapped them to the 700 for my first gravel grinding. They are good tires but not the most flatproof and even though Schwalbe gives them 5 out of 5 for durability, the tread is more than half gone after just a few hundred miles of gravel and dirt/sand trails. Specialized makes the Hemisphere Armadillo in 700 x 38. I've used their All Condition Armadillos on my road bikes for a couple of years and have never had a flat (jinxed that one) and have nothing but good to say about overall performance and durability. But the Hemispheres only come in wire bead and are about 200g heavier than the Schwalbe Smart Sams. I have no doubt that they will be as bombproof as any tire available and very durable (the are designed as an all surface touring tire) but I'm wondering how many of you gravel grinders would add a total of 400g to your bikes for the sake of peace of mind?