Good answer.....

A double a-arm is much easier to set up when the car is lowered plus and is more adjustable. In general the lower you go, the further out you go to keep the lower arm as parallel as possible. You dont have the same constraints as a macpherson strut, or a 5 link. As long as you keep the lower arm parallel with the ground you are in good shape. Also the biggest problem with 5 link is binding and the arms working against each other.

Only problem is Double a-arm set ups is they are really only on open wheel cars or custom racing cars. There are practically no road going cars with double a-arm suspension, unless you look into ariel atoms and other such small car manufactures.