How to repair STL without deformations?

[CuredPrusa]

Whenever I use Netfabb for repair, small round perimeters get distorted.
If I decrease slicing resolution, the result is somewhat better, but never as clean as without "repair".
Does anyone have an idea how to fix the stl open edges without deformation? Does it harm if I leave it "unrepaired"?

[legend069]

This is a very good question!
It entirely depends on the model and where/ whats broken.
Best way is to inspect it with the gcode preview.