I just did two prints. (Slic3r 1.0.0RC2)
0.4 layer height with 10% infill
and
0.2 layer height with 10% infill
The rectilinear infill for the 0.4 height is infill squares ~5mm
The rectilinear infill for the 0.2 height is infill squares ~10mm
Why would the slicer increase the infill like that just because the layer height changed?
All other settings are identical, and parts are identical.