Nice application and result. Do you know the current through the emitter?
Also, how did you dedome the 219c? I have done some dedoming experimentation with the 219c D320. I sliced a large chunk of the dome off with a blade, then sanded it flat with 600-1500 grit sand paper and finished it off with toothpaste. I was able to sand the silicone flat to about 0.1-0.2mm above the phosphor. Like you, I got underwhelming results. I got almost 300kcd at ~5.5A in a UF-1504. Compared with ~510kcd with a dedomed old XP-G2 at ~4A in the same host.