You might like this thread on cardstock:
Base Weight White Cardstock by JRstampers at Splitcoaststampers
I am thinking you are talking about the new white paper SU now sells. I have not used it. I have SU inks, reinkers, and the rest of the items. For watercolor, I basically use Ranger Watercolor Paper, like the Tim Holtz kind only sold in 8.5 X 11 inch pieces. I seem to be using Hammermill for most everything else. My colored is often SU, but also Gina K Designs or any other kind in my stash. I do love coloring with alcohol inks on Gina K Designs white or ivory. I am running out of GKD white, so I reach for Hammermill. It does work but is not as smooth as GKD. I have no experience with Neenah, but do trust other people who love it. I have also used Spectrum Noir white and it works wonderfully on alcohol inks, like the Blends.