Tested in 24.40b8 and up to 24.40b16:Layer Styles that seems now support 16-bit:
Shadow Outside
Glowing Outside
Glowing Inside
3D Shadow
Outline Outside with enabled "Show Two-Dimensionally"
Outline Inside with enabled "Show Two-Dimensionally"
Color Overlay
Window Shades/Tubes (looks like 16-bit, but guess i can see some small additional line artifacts)
Masks that seems now support 16-bit:
Vector Mask Soft Edge support 16-bit.
Raster Mask Soft Edge support 16-bit, only if put any inactive Adjustment layer inside mask layer.
Raster Mask in RGB mode and with enabled Transparency support 16-bit, only if put any inactive Adjustment layer inside mask layer.
Raster Mask support 16-bit, if convert mask to Gray mode and disable Transparency.
Layer Styles that still works in 8-bit only:
Shadow Inside
Outline Outside if use Gradient with disabled "Show Two-Dimensionally"
Outline Inside if use Gradient with disabled "Show Two-Dimensionally"
Outer Emboss
Inner Emboss
Special Emboss
Inner Bend
Create Texture (not sure how to test exactly, but it looks like 8-bit)
Maximum possible Layer Style size is still limited to 100% of layer size. In many situations this is too small.
Brushes are still 8-bit only.