Answer
No, using either of these tools to edit your registry is dangerous because you can inadvertently delete or change keys and values. Neither of these tools has an undo feature, and their user interfaces are not designed for editing safety.
ArcGIS comes with several utilities to allow you, in conjunction with Windows tools, to safely register or unregister components and functionality for ArcGIS. Failing to use these tools may result in improper or corrupted registry keys and values that will likely cause ArcGIS applications to behave erratically. For example, you can use the ArcMap Advanced Settings utility to set many options which are not available in the ArcMap user interface.