Razor61,
Thanks for that link. I think that, perhaps, a "Spinning Stories" thread would be interesting - I have a few! When I have time, I will start one, unless anyone else wishes to (hint!).
Worf,
HUD gearing is the relationship between the angle represented by two symbols in the HUD and the actual angular subtension between them. A "5:1" geared HUD, such as in the Jaguar GR1/1A/T2/2A (and Harrier GR3/T4 and some prototype Tornados) has markings in the HUD that represent climb and dive angles of zero, 30 deg, 60 deg and 90 deg. However, the actual angle between the horizon bar and, say, the 30 degree climb bar is only 6 degrees, hence 5:1. The reason that it was used (allegedly) was that early INs were not accurate enough to support 1:1 gearing. The big disadvantage is that you lose correlation between the HUD horizon line and the real horizon when not in level flight. However, it has the advantage that you do not get "laddering" (pitch ladder moving at too high a rate to interpret it) at high pitch rates, a problem that occurs in a 1:1 geared HUD. In fact, that is why the current Jaguar GR3A HUD only has 1:1 gearing within 30 degrees of the horizon. The pitch gearing is then blended to increase progressivley to 4.4:1 in the vertical. The heading scale in many fast jet aircraft HUDs is also geared (6:1 in most british HUDs) to prevent oversensitivity during heading control tasks, whereas most airliner HUDs have 1:1 heading scale gearing for greater accuracy on a low vis approach.
In answer to your second question, I have not flown the Jaguar International. However, the greatest difference in performance when flying the Jaguar is related to external stores carriage, the extra drag and weight both giving a significant degradation. A "clean" aircraft with no pylons is a totally different machine to one with even just two underwing fuel tanks plus three bare pylons. I suspect that these differences are more dramatic than those with the same stores configuration and different marks of engine.