Hi Brendan, you'll probably get better layer control in Photoshop using AI format for the transfer, since AI has the concept of layers in it. PDF has a thing called "optional content groups" which MoI will use, but I don't think that it will get interpreted as layers when read in.

Then when you do the export, push the "Line style options" button and for the "Visible lines" row set the Layer to be "From Style", then if you have grid lines assigned to their own style that should come through as a layer in Photoshop.

Let me know if that still doesn't do what you need.

- Michael