CrossClimate2s have a 60k warranty though compared to 50k. I'd think a touring tire would last longer than the P Zero which is more in the performance tire category so the rating does make sense to me. With that said yeah I've heard about the loss in driving efficiency, but this is probably because the tire has really good traction wet, dry, or even a bit of snow.
I want to be cautious here because I feel like if we only focus on efficiency, then you end up with those green tires they give Prius drivers with super low rolling resistance but then terrible traction.
I do wish there was a better way to compare mileage efficiency across tires. TireRack's charts make you think that anything is better than OEM tires.
Edit: I should mention that I was set on the Pirelli AS Plus 3s until the sales guy at DT told me about the Elect. I made a quick call after Googling in the few minutes I had and decided to stick with AS Plus 3s, so hopefully I didn't make the wrong choice. 70k warranty is a long time so I'll probably be stuck with these tires for quite a while.