Hi Jim,
Yes it is the D3 controller, Adam Debowski produces them out of Poland. There were a few in use at the WC in 2019, Onda from the Japanese team was using it, I was using it, as well as a number of others from a number of European countries. It definitely gained a lot of popularity during that event. I only got it about 3 weeks before leaving for the WC, so I had limited time to set it up, but I do think it was a benefit for me at the WC.
Adam really developed it initially for his D3 contra systems which has two motors to drive the props, and then adopted it to operate for various other drive setups. Its a pretty simple unit, there is no programming, you need to order it specific for your motor. To set it up you just need to ensure that full throttle is 2000 us pulse output from the Rx, and arming is 1000 us pulse output. Beyond that all the setup is in your transmitter tcurve, and the esc essentially just trys to hit a target rpm based on the pulse input it gets from the rx. RPM is determined from the motor commutation rate as I understand it. Its not an instant response, it does take a short time for the esc to hone the rpm, but it is very good and provides a more exact control of your motor than you are used to. Adam mentioned he has a slightly slower response just to ensure the esc does not hunt for the rpm. Due to this the setup takes a bit of getting used to, as the motor wont unload so you need to be fairly deliberate in your adjustments. Small tcurve changes of a couple hundred rpm at your cruise or idle position has a noticeable impact to the flight speed/braking.
People I have spoken to that have used them and taken the time to get adjusted to it really like them. It does take a bit of time though, the first few flights you may find you are flying too slow because you are used to the reduced braking and motor unloading you get with a normal esc.
The only negative is that if you want to run a different motor you can't and you either need to buy a new one or send it back to Adam to get reprogrammed. Otherwise there is not much to find wrong with it, they are light (~80g), and lower cost than the Jeti's. Since they are tuned for a specific motor as long as you stick with that motor there is no need for any programming anyways.
Chad