2.8, available shortly to alpha partners, now supports formulas in page and view headers. So, if you are using view headers (via view "Tools > Toolbars and styles > Header"), you can now insert formulas, which behave just as with formulas in page/view footers and in the Content view.

Formulas in headers currently don't have a wizard and have to be entered directly using {{double curly brackets}} when editing the header as follows:
This view has {{ RECORDCOUNT() }} records showing
or
Data for category "{{ SUBSET_SINGLETON([My Category Field]) }}"