Great ideas here, especially the plasma fill watercolor effect and now I'm trying Xara for line work/Inkscape for quick color filling.

1. Export line drawing from Xara as PDF
2. Open PDF in Inkscape. Create a layer below the ink lines
3. Fill in the colors with Inkscape's bucket tool at threshold of around 23 and grow/shrink of 0.6
4. Delete the ink line layer (too many nodes when opened again in Xara)
5. Export as PDF
6. Open PDF in Xara and drop the color shapes behind the original ink lines.
7. Adjust color fills as required and mentioned above.

Handy technique till Xara makes their own bucket tool, thanks!

Manoj