I look at it differently. Had you lost those six pounds AND had the Ultra, you would have a 12 pound lighter load. That's the same as 1.5 gallons of water. That is huge!
If you buy into the belief that lighter is faster, then you can't just look at a few isolated items. It is cumulative. You look at saving an ounce here and another ounce there and together it adds up to many pounds. At some point the cost/benefit ratio might not dictate a new purchase, but doing this exercise forces you to be very disciplined with your choices and helps you leave some unnecessary gear at home.
The best thing I did before the EC was to take a backpacking friend's advice and I got a 5 pound digital postal scale. I weighed everything and make substitutions where I could save weight. Even a minor change, like changing to cuben-fiber dry bags saved me over 2 pounds of weight alone. Unfortunately doing this also makes your wallet much lighter in the process....
Having said all of this, increasing fitness and especially technique will yield much bigger rewards than just reducing the weight of your gear.
I don't know how the Ultra layup fares to oyster shells as compared to the Performance layup. Oysters cut, scratch and abrade the hull, it's not like the blunt impact of hitting a submerged log which is what I understand the "archilles heel" of the Ultra layup to be. That would be a good question to ask Brian Houston.
Greg