The worm gear is great- I use a 30:1 worm drive in my belt driven Z axis. It's a little hard to tell from the photos, but it looks like the belt path isn't parallel to the Z rail. That's going to lead to layers being squished thin at the top and bottom of the machine's Z range. You may never see the top layers squished thin, but you'll see the bottom squished in every print. Maybe it's just a bad photo...
Ultra MegaMax Dominator 3D printer: [
drmrehorst.blogspot.com]