Egg, I see that happening.

Your SVG has a size of width="666.001" height="385.001".
I trimmed these to width="666" height="385" and the lines were much reduced.
Sorry Acorn, missed that post. I agree with what you're stating there, however I noticed the exported svg pixel sizes when opening in Inkscape. The cutting 'rectangle' within Xara states whole (integer) pixels but the export gives decimal place W x H. I've tried many methods to reduce this effect i.e. reducing the svg size in Inkscape to whole units an re-saving. but the incomplete tiling remains. I can reduce it but it's never perfect. Sometimes it is but often it's not.

I'll try your method of restricting the image to the square root of three but this is very restrictive. Just endevouring to get the 'cutting' rectangle above a vector shape is hit and miss re tiling. I can easily achieve it using png's but not simple at all using Xara generated svg's :-(