I didn't really take it personally, but to address a couple points you've raised:
When my current batch top-crops I'll skim some yeast off and make a batch of the same beer with D2 instead. It won't be the same size batch, it won't be brewed on the same day as the first batch, with the same wort, or with the same ambient temperature, or pressure, or yeast pitching rate, or lunar cycle, or zodiac sign. I'm sure there are a hundred other variables that won't be the same, either.
Since I don't have a lab to work in, I can't really control all the variables. Where do you want to draw the line? How many variables are necessary/practical/preferable to control?
I'm not pretending I'll win "scientist of the year" with my experiments, but I do think it's informative if, in my first test batch, one was not obviously 'better' than the other. If I can't tell the difference between them, that tells me they're "close enough" for me.
Are they close enough for you? I can't answer that, and I don't particularly care. Only you can answer that. If you want to buy D2, you should buy D2. If you want to make your own, you should make your own.
Orangehero and ODaniel have suggested that pH may have an effect on the flavor compounds created. So I'd say if you want to strike out on your own, I'd experiment with adding varied amounts of KHCO3 before the DAP to see what happens. I had some paid days off a few weeks ago when I did most of my experiments, and I don't know when I'll have time to try some more. But that's where I'd go next.