Is there any solution when the minimum size of the dynamic cursor is too big, other than deactivating the dynamic size?
Make model larger 
I can’t, all my models are based in this scale. Also it is not an odd scale. It is the same scale that uses the Nick male model included in Zbrush, where a character with GOZ gives 1.83 meters when sent to 3ds Max. Also it works fine with all programs with a clean translation of scales with the correct size. The only issue is Zbrush with the dynamic cursor. In this case because I’m doing a model bigger at the same metric system, a truck instead than a character, it seem that the minimum cursor has become larger.
I would disconnect it some times removing the dynamic switch but Zmodeler doesn’t like that, not only complains, also stop me changing it.
Turn down Preferences>Draw>Dynamic Brush Scale.
Thanks again 