OK the *simple* numbers.
As noted 1MW = 1341 hp, but we're given the 2 nacelle rotors are 600hp and the drive is 300hp anyway.
So (assuming the drive engine, which is 300hp) drives these for every unit of time the ascent process takes it needs to run (roughly) 4x that long to charge the batteries for the takeoff.
That's important because the longer that process the heavier the batteries get.
Note this hybrid drive concept is not quite as you might think. Mechano/electric/mechano conversion is highly efficient (it's the thermodynamic chemo/mechanical conversion that stuffs the efficiency). High speed generators and motors can be made very compact and eliminate both the huge gearboxes to step down the gas turbine to rotor speed of the Osprey and its monster cross coupling shaft.
It also help that it's unlikely they system will be designed to allow you to open the doors in hover and rappel to the ground, or offer covering fire while remaining in hover mode.
Note the rate the energy has to stored and dumped sounds more like a supercapacitor application, but I think their capacity Vs volume and mass is not quite up to it.
Is the SoA in batteries, motors, generators and power electronics in general up to it?
Maybe. Or close, and this is an area that where development (for other reasons) is moving quite fast. This architecture can leverage developments elsewhere in a way the Moller concept (high power to weight Wankels are pretty specialized) could not.
Could it be a money pit like Moller? Definitely. The fact they have not got their 1st model certified to fly does not encourage comfort. But (counter intuitively) the more complex power conversion may make the task simpler.
I'll wish them a (skeptical) good luck.