I like the thinner paper myself, if NXM Omnibus uses this 'thinner' paper, it's cool with me.
I thought the paper in the ASM Volume 1 I own was entirely too thick. It makes the books too thick and heavy to really read for long times comfortably. The perfect paper would be the kind used in the paperback Masterworks.

Oh and I also vote 'yes' on the new spine and cover designs...so much more character than the bland silver debossing. Although it would be even better if the designs were unique to each book, a la the X-Statix Omni, but I'm probably in the minority on that one.