I think the giant wurm was quite a grainy print, so the layers are pretty big. Think it was 100 microns (the print file details suggest 0.1 which I assume is mm, so...). The painting technique rather over emphasises them anyway (dark base colour, highlight, magic wash), a more subtle approach might minimise them.
For tiny buildings the grain might look like over the top - I suspect on larger buildings that should be a big rough it could actually help, give a bit of depth/relief to the larger blank walls for rough stone, plaster, bricks etc?
Think you'd have to give it a bash and see... and if it's not suitable for 6mm, use it for bigger stuff
Dragoman on Shapeways has piccies of actual buildings he's done -
https://www.shapeways.com/shops/dragoman but I don't know how they compare to a desk top printer in quality...