We’re seeing some pretty significant errors (and overall differences) between 32-bit and 64-bit renders.
In our particular case, we see it in shadows, but it may not be limited to that. We’ve only seen it in Schlick renders, not in Phong, but that may be because the Phong renders we do have very poorly differentiated shadows (since you are mostly seeing just specular highlights).
Not sure if anyone’s tested a mixed x86/x64 render farm, but we had a rare instance of renders using less than 2GB, so we thought we’d try it out. Voxel rendering is rather kind to low particle counts.
Edit: This was 1.5.1.38002, 3ds max 9.