The odd number indeed served me well in the end. Especially the Conway's Game of Life benefits from this by giving very nice patterns because of the true center line. My alignment is off by up to half a centimeter in some lines by the way. I can still fine-tune quite a few, but it won't be perfect (but I didn't expect 'perfect' anyway )
I'll open-source the code in a few days, when a few bugs are resolved.