Are you refering to FCAW-G using CO2 and self shielding FCAW?

Ok I got your PM and the criteria for selecting one of these two processes would be where and what you intend to use it on.  FCAW-G using CO2 is mainly used in a controlled enviroment where high deposition rates are needed in out of position joints. Straight C02 is less expensive then your Argon/CO2 mixes and can be used with certain wires that are designed to weld with straight C02.  Some wires are designed to use both straight C02 and a Argon/CO2 mixes, but your arc characteristics won't be as good as one that is designed for either or in my opinion.
   For FCAW-G in a controlled enviroment, it is less likely for wind to blow away your shielding gas and such. FCAW is mainly used outside in the field where high deposition is needed in all positions.  It is not effected nearly as bad as FCAW-G is by wind and such.  Hope this helps.