Hello dschlotz,
You must be pretty busy since I haven't seen you post in a while... Kobelco welding filler wire is probably one of the best CO2 or Ar/Co2 mixed gas FCAW wire out in the market today and has been for some time now... It's an excellent wire that runs as smooth as a baby's behind IMHO... If I were to choose between the Kobelco and the ESAB it would come down to availability and cost factor but if expense isn't an issue, then hands down it would be the Kobelco... The only difference in shielding gas choice is this... With mixed gas of75%Ar/25%CO2, the voltage should be turned down 2 volts than what is listed as suggested welding voltage and current to stay the same... The Japanese have perfected CO2 welding with FCAW or GMAW...
I would give a slight edge towards ESAB should we be limited to use the mixed gas exclusively... I have used both brands in a variety of situations and they're both excellent with respect to weldability, and the choice to make between the 2 should be based on the factors I listed above as well as consideration being given to service conditions, and project specifications and in order to make a choice based on the better overall weld quality by welding some samples of both brands... And then run the Macro's, and Mechanicals to evaluate and to help make your final decision... Good luck and I hope this helps.
Respectfully,
Henry