The WYSIWYG module in Drupal is a great way of integrating a client side HTML editor (better known as a WYSIWYG editor) into a Drupal site. It supports a variety of different editors, all of which can be configured depending on the input format being used by the user. The ability to incorporate many different content editors into a site using a single module means that the configuration interface for them all is pretty much the same. It also means that it isn't a disaster if a different editor is needed for an existing site. You just need to ensure that the correct configuration options are set to allow a similar user experience.