Get the AD400 for a minimum. I have both AD200 and AD600 and use AD600 a lot more. AD200 is nice, weight wise but that's it. LCD is pain to read outside. I know I don't need to read it except when I was using the wrong trigger Nikon on my canon camera and had to look at that tiny LCD outside in the sun. AD600 is much much better in that regard. 2nd extension head but now AD200 has it. Third less need for snadbags as I can put my AD600 down below on my light stand. 4th, two AD200 in that dual head is more pain IMHO.
Power wise, if I am shooting in the sun, I need two AD600s with the dual head. I currently don't have it.
Bobby, what kind of lighting conditions would you be shooting in where you would need that kind of power? Or it is it more of a distance thing, where you would need the power to push more light farther?