That's my point: what experiments could be performed have been performed, and have failed. Also, it is a massive weakness of the theory that it can be used to

That's my point: what experiments could be performed have been performed, and have failed. Also, it is a massive weakness of the theory that it can be used to predict such varied values. This is a big part of why it is not exactly a scientific theory: it is not really falsifiable, since you can tweak it to predict any value you want. If we had the kind of particle accelerators needed to test high-energy supersymmetry, and if it failed again, it could be adjusted to predict higher-energy supersymmetry, and since the number line extends towards infinity, this would never stop.