Checking if depth >= 1.0 (sky), does not seem to work for dhDepthTex1, but works fine for dhDepthTex0.
This behavior is different from depthtex0 vs depthtex1, where both can be used to check for sky (as long as there are no translucent blocks in the way).
The screenshots show me testing for sky (and setting color to red if true) for depthtex0, depthtex1, dhDepthTex0, and dhDepthTex1, respectively