I heard about this from another tile setter in the US and he really likes it.
I haven't used it ...yet. But the next large format stone job that comes up I will most definitely be pricing this into the quote.
The first truly simple marble, slate, granite tile leveling system...

This video shows actual marble tile installation using the Tuscan Leveling System. During the actual installation 124 square feet of marble tile was installed in ONLY one hour. This video shows the installers walking on the tile while the mortar is still wet. You will notice the ease of installation and the simplicity of the product. You will also notice that the level is hardly used throughout the installation. Yet at the end, after all the straps have been tightened, you will see that the tiles are virtually lippage-free.

It is expensive, but the advantages seem to outweigh the cost.
When I use it I will let you guys know the results.

We had a look at these in this thread mate,

Would Like To Try These!!!

The concern is whether or not you can get the coverage when the system appears to lift the tile to level it with the next, if you try them you'll have to let us know what its like in the flesh

what a sack of grap when the tiles pull the next one up you will get voids under the corners

keep us posted mate...

Seems a bit OTT for tiling. I'd want to rely on my own marks I think, as I'd be working out where the tiles will be sitting not just if they're sitting level sort of thing.

Using that, or any leveling system, you'll get some level datum lines on the walls but then you're back to using a guage staff / rod / stick or some measurements to work out where the tiles actually sit.

So in theory - it's a process extra anyway using that system.

Perhaps for the odd huge room that's pretty square it would suffice. In any other I can't see it working as well as you'd like it to I think.

the main problem is the massive cost. some one is on a 'get rich quick' there