The guys that use the bullydog injectors like them but VERY few have used the same stage from Bully and DD and as far as I know no one has run them head to head on a dyno so comparitive data is little to none. My OPINION from seeing the Bullies run is that they are a little smokier, but there is no doubt they make the power. For me I will stick with DD injectors as I know them to be first rate, the guys on the other side of the fence say the same thing.
I really doubt you will lose any bottom end power, but don't know for sure. I would think that power across the board will be up at least somewhat. I have run 1's and 3's from DD. I thought the 3's were a little weaker on the bottom, but a large part of that is because the big end is SOOOO strong. I do know I can't make the boost I used to with the 1's at 1400-1900 RPM, I am probably 8-10 psi lower, but with an auto transmission that is a good thing. Besides, I go through that RPM range in a flash and once over about 1900 the 3's FLAT SCREAM!!! The DD2 is known for a real solid low end as reported by guys that have run the 2's and the 3's, and for having lower EGT. Email or call Bullydog and ask them, if anyone would have a definitive answer it would be them.