Double zero
I am not a harrier pilot, so I stand by to be corrected by someone who is, but I have shot/chased a lot of them in my time (and ok I think once one may have shot me
) and your comments on the speed/stores is, I believe true up to the 450ish mark. Somewhere around there they hit a "wall". I don't think I have ever seen a harrier do 550, for example (not saying it can't).
They tend not to run away because they can't, and if you integrate them into a COMAO you have to take into account that they are appreciably slower than most other FJs.
Also would be surprised (and hurt) if the GR1 was faster than the F3 - the F has tweaked engines, the extra length makes it more stable trans/supersonic.