Yes the DT is proprietary and they give you an extra in the spares bag. I don't understand why Hussar went with a proprietary DT. It's like one step forward with top fill and one back with a proprietary DT.
I will see what parts are interchangeable on my next refill and report back.
Ha, I will try and build the Franken X ...
Side trip: I don't know if you are still looking at RDA's or not. I received the VA Apex and Haku Venna clones and have them on Luna's. Both are very serious flavor bangers and in your wheelhouse air wise. The Apex is an impressive design in that it would be extremely hard to oversquonk with plus it has a deep juice well. I really like both, a lot. It would also be difficult to oversquonk with the Venna the way the airflow is designed on an angle. Flavor wise they are right there with the Hussar v1 RDA.