Duplicolor or Summit paint?

Going to try and paint car soon...was wondering how much paint I will need to sucessfully paint my 72 dart...I like the fact of the duplicolor does not have to be mixed....but the only color I like is the Dark Emerald Green Metallic.....and the no time recoat period...the summit racing color is the Sour Apple Green Metallic and requires all the reducers etc......anyone have experience with either of these?...I really need more info an the paint shop brand from duplicolor...thanks