There used to be render differences with Alpha CPUs as their random number
generation was different than Intel and Mac systems. NewTek did fix this
issue though. Anyway, there are no render differences between platforms
with LW now as it uses the same RNG code on all platforms.
Sounds to me like the RNG seed value is getting lost when the scene is
loaded up on his render nodes. I guess if Tuvok could post his scene (or a
portion of it) maybe some of us could take a look to see what's going on.
There could be a glitch with his scene or surface files -- did he recently
change LW versions in the middle of this project? Or it could be a network
path error within his render farm setup... It could also be an issue of how
the texture orients itself to the rest of the scene (World Coordinates
possibility you mentioned).
Another possible workaround besides rendering on one system and comping
would be to bake the procedural sky texture - but if he needs to animate the
texture over time, then that won't work. If he hasn't done so, he may need
to save the sky texture out as a surface file so that way it's on disk with
the proper starting seed value right there in the file.