If both tools are rotating at the same revolutions, the larger pad has a much greater chance of damaging the surface (for the reason you listed).
The Nano uses a 1.2 inch pad rotating at up to 5000 RPM. This sounds scary at first, but it is really the same speed (more or less) as a 6 inch pad rotating at 1000 RPM. It offers ample cutting power but remains fairly friendly to the paint (unless you hold it still and allow the temperature in the paint to climb).
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