This is the fastest welder for Stainless Steel. You need to make sure your using the correct CO2/Argon gas mix along with SS wire. You can also use SS wire with a flux core. Then you won't need the gas.
Another excellent welder for SS is the TIG. It makes excellent looking welds but it is slower and requires more skill.
I'm not a welder. I just turn it on and let the sparks fly.