Thanks for the thread, FP.
Both of the systems you mention are relatively inexpensive knock-offs that raced to the market after the original Tuscan Leveling System was invented by one of our members on this forum. They definitely have the short comings you mentioned.
I’m not trying to be a snarky or anything when I say this: you want to know the secret to installing tiles really flat to each other? Prep the floor so it’s flat as a pancake. That, alone, will improve the flatness of your final product by a great deal. But prepping a floor is vastly overlooked and under-appreciated…even by some pros that have been doing tile a long time.