That's looking fabulous, Iceblossom! Call me contrary, but I prefer the white cornerstone; if you look at your thumbnails above, I think the gray gets more lost than the white, whereas the white draws the eye to the center, and then you take in the whole block at once. With the gray, my eye is wandering around the thumbnail block trying to find a focal point. Your instincts were great for picking your substitute colors!
This is the first week I felt like ditching my Indigo Way and focusing on the mystery, but I'm telling myself that my way to the mystery units is through my UFOs. I've started on my bottom half of IW.