I did my own experiment (based off your experiments) with Organic Cane Sugar (not pure white) and Organic Turbinado Sugar.
Syrup #2:
1.5lb Sucrose (Organic Turbinado)
1.5c H2O
Added 3/4tsp DAP, added @ 210*
Heated mixture to 260*
Added 3/4c H2O
Heated mixture to 320*
Added 3/4c H2O
Syrup #3:
1.5lb Sucrose (Organic Cane)
1.5c H2O
Added 3/4tsp DAP, added @ 210*
Heated mixture to 320*
Added 3/4c H2O
Heated mixture to 310*
Added 1.5c H2O
Syrup #3 with the regular Cane Sugar turned out great. Near black in color. Tasted great but didn't get those chocolately flavors D2 has.
Syrup #2 was a pain in the ass with the turbinado. I kept trying to foam over. It took a long time, and the only reason I added water at 260 was because it didn't look like there was much left. After a hell of a time keeping it from foaming over the pot, I finally finished, and it was fantastic. Got those chocolately flavors that D2 has. I plan to do them both again, and maybe some other experiments. I didn't have time to really take tasting notes or anything else because I was brewing and it went in the kettle shortly after I was done making it. They both went in a BDSA with Trappist yeast and Brett Brux. Can't wait to try it in 6 months, and a year, and 2 years. I'll try to take some notes and compare to D2. I'm not trying to clone D2, just trying to get something awesome.