So for the moment it's a fixie - kind of nifty looking but without the ability to change gears anyway somewhat pointless...

Hmm... looks nice, but: - aah.. how does it change gears? that's far harder said than done.. - is it comparing efficiency to the default Dura-Ace chain system out of the box? Because the default chain oil used is sticky like honey and is renowned for its friction... everyone cleans that right off and uses a lighter oil.

@f8lee, it clearly isn't *meant* to be a fixie. You are just seeing Stage 1 before they complete the project with a 13-speed mechanism.
Extremely not-pointless. In fact, it is the end of the derailleur for those who aspire to the best.

Even if they can solve the gear change problem with a sliding pinion, that flimsy gear-set will flex so much that the pinion rollers will jump teeth on the bigger cogs. It's a "no" from me.

it does not change gear and it is a tiny amount more efficient that the system that does Guess what if I modify a derailleur system so that it does not change gear then I lose that inefficiency as well!! - so the gear/chain system will be just as efficient as this monstrosity

Never thought of the derailleur system as inefficient. It certainly doesn't hold anyone back from the enjoyment/workout it gives. Was hoping for a video demonstration. The cassette diameter will be prone to flexing, as Johannes says, can't change gears yet, and what is the weight difference between the two methods? Is this meant for competition cycling? Would the average cyclist have incentive to buy it, and at what cost?

I like it a lot, but it will have to be made very strong.

Here's the problem with gear changing;
In order for the "pinion" to move back & forth through the "cassette", each of those rings will need to be separate parts. And will somehow need to synchronize with each other. Even if that is possible, you’ve now added a good amount of complexity. And, therefore, cost. T N Args is mistaken. The derailleur isn’t going anywhere, anytime soon.

All it needs is a freewheel at one of the three rotation points and a spring loaded sleeve on the shaft.

This is remarkable