Hi Brendan, I can't seem to find anything wrong with your file, do you have Illustrator available to test loading into it? MoI writes an older AI v8 type of file which Inkscape does not know how to read, Inkscape can only read newer versions which are the same as PDF format.

Are you able to organize things in Photoshop by color or lineweight instead? If so then you could use PDF format. I'm traveling for this next week and so it's a little difficult for me to examine your file in detail with other programs, I can check it in more detail like loading it into Illustrator next week.

- Michael