Hmm interesting. I do see the weight reducing effect of Fresnel lenses but I don't see how you will gain any room. In the DK2 it's not the thickness of the lenses that prevents putting them closer to the screen.
And using Fresnel lenses comes at the expense of lowering the imaging quality.
Oh, I assumed since the DK2's thick lenses touch my eye lashes, the thinner Fresnel lenses would be further from my eyes. While image quality is lowered with Fresnel lenses, the bottleneck may still be the screen resolution, so the lenses won't make a noticeable impact quality wise.