Interesting! I have honestly never considered that! I would not really be able to calculate the offset per-island per-layer, since each layer's sparse infill needs to bond with the previous layer's sparse infill, so it's a bit tricky. And the resolution would still be the same as the extrusion width. So, I could probably set it up so the pattern is centered in X and Y around the exact center-of-mass for each sub-mesh, which I could see working for some cases, and not for others. Or, commit the ultimate crime and add new "Sparse Infill Pattern Offset X & Y" settings. [8^)
Thoughts?
Jonathan