I'd love to know how they are running the shaft from the turbine to the compressor .. these things spin at something like 100,000RPM if I'm not mistaken. Normally this would be handled by a few bearings with direct oil intake at high pressure with the bearings being only a few centimeters apart if that .. but to span an entire engine is some special kind of precision engineering.
edit: special because any imbalance in the shaft would rip the bearings apart.
The motor/generator sits in the middle of the two turbines so that can help keep shaft length down but gearing 280,000 rpm down to something that wouldn't blow up the motor creates a whole new world of complexity. All I know is that this is very impressive engineering and that there are tons of unique innovations needed to make it all work together.
edit: special because any imbalance in the shaft would rip the bearings apart.