The following changes have been made to the GLTF model loader:

• Correctly loaded rotations and orientations.
• Mesh collision caching for faster loading.
• Supports transforms with negative scale and correct face orientation.
• Support for adjustable alpha cutoff value.
• Support for KHR_materials_unlit extension (full bright materials).

This model from SketchFab was useful for testing because it uses so many features of the GLTF format:
https://sketchfab.com/3d-models/ftm-0970f30574d047b1976ba0aa6f2ef855

This scene uses alpha masking, transparency, and the full-bright extension, since it already includes lightmaps. The cartoon outline you see on the edges is actually mesh-based.

Update is available now for beta subscribers. At this point, if you find a GLTF file that does not load correctly, or if there is an extension you would like to see support added for, I would like to hear it.

I'm also proposing standalone GLTF material files here:
https://github.com/KhronosGroup/glTF/issues/1420