I've used argon and argon/CO2 on stainless mig and the results are "acceptable" but below -- with hobby type migs -- what you'd get with the cheapest TIG. You've also got the issue of spatter and the -- depending on the job -- issue of sheilding the back of the weld.
I gather there are gas mixes which may suit the process better.
All I can really suggest is try it, only you know if it's acceptable or not.
Tidyness, operator skill is going to be a big factor but as said hobby type MIGS make it harder than if a set with adjustable inductance were used
Pure argon doesn't work well with MIG (aluminium aside), too much CO2 in the mix can cause problems 'down the road' and results in dark welds. There are specific mixs available, stainshield for example- helium/argon + a little CO2 i think