I remember there being discussions on here when it was thought that the XF should be a bit more technical....i.e. more emphasis on the actual technicalities of the singing etc, which is where GB was supposed to come in....
Though I think tbh if the XF suddenly went all profesional and had serious people on the panel that were all singing teachers, the show would bore everyone to tears!
I think its strength is in the "entertainment" of the show, the judges quips, the put downs, the judges chemistry, and lastly to some degree, the actual contestants!