From my first quick look at, it seems to me that this is a workstation. Tyros4 is not on the same category, it's an arranger. Here, we can see the demo on how to use it, is more of a studio production tool instead of a live performance like Tyros4.
You and I know that... but the person from Open Labs is misleading the people leaving comments on YouTube. He's saying the tone quality far exceeds the Tyros. He also says for a simple $99 software update, the StudioBLADE will do the same things the Tyros will do. It's just misleading.
The StudioBLADE is a computer to run your DAW and plug-ins. They just build it in different keyboard configurations. And yes, you are correct, the StudioBLADE is a DAW workstation and not an arranger keyboard... even though the rep from Music Computing says it can do all things Tyros but even better with a simple software update.
Also, the piano sound in the demo I posted doesn't sound as good as the SA Piano sound on the Tyros 4.