Backwards compatibility is rarely an issue, it’s going the other way, from the more advanced, newer arranger to the older or less advanced one that often presents problems.
If it is possible to copy the DGX styles to a stick and play them in the Genos, I would expect the normal ones to play fine, but the Pianist styles rely on technology the Genos doesn’t have, the ability to switch between Variations depending on what appears to be either velocity, or possibly note density in how you are playing, and also maybe thinning out the number of Parts playing in response to you as well.
I haven’t seen one yet, so I haven’t yet had an opportunity to pick apart the system Yamaha use, but I do know there’s nothing in the Genos that can do this automatically. Sure, you can use buttons and foot switches to achieve some of this, but not without you having to stop playing and go press stuff, which kind of defeats the whole point of the feature… You just keep playing like a pianist (both hands busy!) and the arranger figures out what you need.
The good news might be, if this system is well received there’s a chance that Yamaha might update the Genos/SX OS to include it, or include it on the next generation, and piano playing arranger players could rejoice without having to lug around a pretty oversized 88… 😎🎹
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An arranger is just a tool. What matters is what you build with it..!