Its important to note that the entire ASUS line has added EAX5.0 emulation via their drivers, something that wasn't avaliable yet at the time most of the cards reviews were written, which is a major plus.
I prefer the D2 mainly because:
1: Less chance of incompatability (No floppy power connector, no PCI->PCI-E bridge chip)
2: Sererate Optical input, Optical output, line input, and line output ports (VERY few offerings have all 4 of these as seperate ports).
VERY simmilar either way though. The only issue I have with the card is its not in a particular good price, with the D1/DX/Striker almost as good for a cheaper price...