I've got some Vision X s4100 on my bumper and some D2's on my windshield bracket. I did order some Dually's to replace my fogs but they haven't come in yet. The D2's I have are a driving beam, fog/spot all in one and the Vision X I have are spot. In some respects the Dually give me more usable light, nice wide beam, 100' to 150' wide and about 200' in front of you. If I was to do it again with the Vision X, I would have done a Euro or flood beam with them. I've adjusted them up a little higher and about 3 degrees to the outside, so the light is more to the sides.
Depending on where you put the D2's they could look small... try them in some different places and see. I had someone ask what they look like on my PSC brawler bumper... didn't look good on the top of the hoop.
Hope this helps, let me know if you have any other questions.
Steve