Typhoon,
It really depends on the threat environment. The Typhoon can 'self escort' in a moderate threat scenario, the GR4 armed with only AIM 132s and guns can't.
If you increase the threat then you would deploy additional AD Typhoons as escort fighters...either to protect the GR4's, or bomber Typhoons.
Now back to the question, in an AD world we would 'try' to preserve enough of the primary armaments to fight our way home. The gun wasn't a primary armament, but a very useful one! It is not, and never will be a "Sovereign right of self defence" weapon. There is no such weapon...I guess the Taser might cross that boundary...Useless air to air though. (Someone will now produce film of A-A Taser trials)
If, in the land of airbourne reloads, the magic man came along and asked "What you want fella" my answer would be "A couple of those AIM 120 thingys and as many 132s as you can cram on the jet" Oh 'Please' would have followed.
Would I have rather had the gun over 2 extra AIM 132s???? No.