Let's clear up some misconceptions first.
The border width on Warlight *does not* depend on the width you set in the SVG file - it will be overwritten. That's why you didn't see any change.
However, the SVG file border width should be adjusted to be the same as the WL border width - so you are seeing the same thing on the site and in Inkscape / other editor. Currently I'm not sure what the width is (it was supposed to be 1.4 px wide, but Moros's test seems to indicate it's actually 1 px), but you should determine it (just look closely at some detailed part of border on Warlight and adjust widths in Inkscape until images match).
Also, I think you know this, but for posterity: if the territories you draw have overlapping border, they will not magically un-overlap when uploaded to Warlight - you'll have to do it by hand.
Right. Now your border widths are perfect (make sure they are the same on all territories!). Do borders between bonuses overlap? If no, great. If yes, do this:
Consider two adjacent territories, belonging to different bonuses, with (maybe partially) overlapping borders. What you need to do is this:
* copy first one, paste it in the same place (Ctrl-Alt-V), convert it's stroke to path (Path -> Stroke to Path)
* do the same to the second one
* select first object and outline of the second, use Path -> Difference
* select second object and outline of the first, do the same
* the borders should now no longer overlap, just touch
This is boring work, since you need to do this for every pair, but it requires little to no though - just "automatic" clicking and using keyboard shortcuts. Maybe it could be actually automated - I'll try to look into creating an Inkscape extension for this next week, when I'll have more time. (No promises.)
[I copied the above from my response to earlier thread: ]http://warlight.net/Forum/Thread.aspx?ThreadID=2925]