I like good old fairy, tried gg4 and didn't get on with it. Agree with all that tosh said. As for making the window attract dirt, thats great it gets rid of the not today thankyous. I'd like it if the wfp windows got dirty faster to be honest, going back to clean clean windows doesn't seen challenging. It does leave a film behind, but the windows look good, however if you are thinking of switching to wfp in the near future then I wouldn't touch it.
Simon.