I am using inputRichText as follows:

<ice:inputRichText
  id="#{id != null ? id : idGenerator.generatedId}"
  height="#{height == null ? '100%' : height}"
  width="#{width == null ? '100%' : width}"
  toolbar="#{toolbar == null ? 'Basic': toolbar}" value="#{property}"
  language="de" skin="#{skin == null ? 'office2003': skin}"
  disabled="#{disabled != null ? disabled : false}"
  rendered="#{richText != null and richText != false ? true : false}"
  customConfigPath="css/config.js"
  saveOnSubmit="true" >
</ice:inputRichText>

<ui:include src="../../templates/input.jspx">
  <ui:param name="id" value="notizenRichText"></ui:param>
  <ui:param name="richText" value="true"></ui:param>
  <ui:param name="height" value="300"></ui:param>
  <ui:param name="toolbar" value="AZSuisse"></ui:param>
  <ui:param name="property" value="#{offerte.displayNotiz}"></ui:param>
  <ui:param name="disabled" value="#{offerte.offerteGuiDisabledState.offerteBeendet}"></ui:param>
</ui:include>

setter for the property:
public void setDisplayNotiz(String notiz) {
  setNotiz(notiz);
}

With saveOnSubmit="false":
- when deleting all text and pressing 'save' in the toolbar -> null is received by the setter

With saveOnSubmit="true":
- when deleting all text and a formSubmit takes place afterwards -> the last value (and not null) is received by the setter