Interesting presentation Nick. Puts the facts into perspective.
"Someone probably has an ulcer by now."
Certainly looks like some serious engineering has been required...
"... electric drive systems ... improve in efficiency, reliability and weight.... a mission-optimized powerplant located on the aircraft's fuselage driving motor-driven proprotors..."
I'm a complete convert of the hybrid helicopter, primarily for reasons of improved efficiency without mission compromise (generally through v-RRPM). Best power/weight is using NdFeB magnet technology, in a disk motor to reduce the iron reluctance circuit mass. Commercial units already exceed kW/kg by running at very high rpm (couldn't find an exact figure by googling).
My only concern is that you will always need to design for failsafe operation, primarily due to the controller complexity required for brushless DC motors (magnet rotates, while static windings are switched). In a tilt-rotor this means you always need the tip-to-tip driveshaft, in case one motor fails. You can triple up of course, but i will be interested to see which way the technology goes...
Mart