Stock Honda wins on all counts and by a wide margin. As a practical matter, DD2 exists solely as a class in the Rotax Challenge series, and a small class at that. If you want to race that series and make it to a national or international final, then DD2 might be a class where the competition level and numbers give you a better shot at advancing. Unless that’s your specific goal, run stock honda.
We have a very good (international competitor) DD2 driver show up at our local track on occasion. He gets put in with the shifters and runs back-to-mid-pack, surrounded by drivers definitely not at his ability level, purely because the DD2 is markedly slower than the stock Hondas.