Musket again

Not too sure of your point regarding sat nav. The corrections are built in.

Corrections? What corrections? The programmes in your sat nav use General Relativity to calculate your position because it gives a far more accurate result than if they had used Newton's Theorys.

The extraterrestrial trajectory to Mercury has such a low velocity in terms of c,, time dilation is irrelevant. Earth control time delay is a factor but Newtonian calculations will land you where you need to be. You have to reach 0.8c before time and mass start getting interesting.

Yes, I know. From my previous post - It isn't about time dilation due to high velocity, it's about the curvature of space in the presence of massive bodies.

But in the observable realistic achievement stakes

Yes of course. In the observable realistic achievement stakes Newtonian mechanics works just fine (most of the time). It is a very useful tool for calculating how long it will take you to hit the pavement and how fast you will be going if you jump off a tall building or for working out how to navigate a spaceship to Mars. (It might have a bit more trouble with a game of billiards but, in principle, it can be done.) That isn't enough for a scientific theory. If a theory makes a prediction and it doesn't match the experimental results. it ain't a theory no more. Mercury doesn't go where it should and clocks in orbit don't run on time.

Interstellar distances with high acceleration, I grant you, we need to take time and mass as variables that would alter the target had we stuck with Newtonian calculations, but even then we would be introducing variables, not superseding.

What are you saying? That General Relativity is just Newtonian Mechanics with fudge factors? I think there may be more to it than that.

Why do you keep on about Quantum Theory?