Here's what no QL fan will ever tell you, none of them have ever actually measured pressure.
So when they tell you "it works and it's really close" what they mean is they dialed with burning rates and start pressures(which is ridiculous and always zero) until they got the chronograph to match the prediction. Then the their hands up and proclaimed a victory in the name of logical fallacies....
Groupe SNPE powders, QL is rather close to reality. Legacy Thales powders before the arsenal was torn down and the process completely changed, not terrible.
General Dynamics(especially the progressive powders) and several Rhinemetal powders it's flat dangerously wrong.
So "is it worth it"? Depends on what you think you know, Vs what do you really want to know?
If you think "Alliant" or "Winchester" have actually made powder in the last several decades. Then no, QL isn't worth it and you will lead yourself down a path of false information and won't actually learn anything.
If you think the "brand that's true" doesn't flip flop suppliers, like your teenage daughter changes outfits; then it isn't worth it.
The GRT fans are in the same boat. Gordon died several years ago, and took the source code with him. Those of us who measure pressure and were contributing to his calculator, all stopped sending data in because they can't change anything.
Now on the flipper.
If you're one of the few QL users who doesn't pretend it's the Oracle of Delphi, then as you know it's a great tool. You can get an idea or a direction for something, that you can them go out and actually measure the pressure on.