microsoft are the only people with the source code to notepad, and ironclad games are the only people with the sourcecode to the convertdata*.exe's, so a single program to edit the entity files in binary is not likely to happen, but a program that uses the convertdata*.exe's to convert then open the files is possible and there is a sins gui converter already released in this thread
there is a sins editor already released in this thread but it was released before entrenchment so does not know about the name change for the convertdata*.exe's
the existing convertdata*.exe's are intended to be run from a batch file or called from within another program to do the conversion to/from binary and text, and only convert ONE file at a time.
other than my own utilities these are the ones I found in a 21 page dive through the forums
hope this helps
harpo