Hi,
It seems like Cura 2.5 (I have not checked other versions) is slicing in under-extrusion on some walls, see the transition circled in red in the image:
layer view
By the way, Cura 2.5's layer view is awesome for showing this :)I saw gaps between the walls on my actual print, which is what made me investigate. What I see in my physically printed object matches the layer view pretty well, i.e. the wall lines that appear solidy connected in the layer view also seem solid in the print, and th ones that look underextruded in the layer view have gaps.
I wanted to attach my cura project, but it seems that the forum does not allow this, but I cannot really imagine what I could have done to cause this ;)The model is from this thing: http://www.thingiverse.com/thing:1784375