I have also used normal steel gas in combination with stainless wire to weld stainless, and it worked. Probably there's a bit more splatter or something only a professional would notice. The joints will be blue afterwarts, but there's an etching paste especially for this. You brush it on, wait an hour or two and rinse it off, then the stainless will look as before welding. The blue colour is only on the surface and this paste contains acid and just removes that thin layer. It should be rust free again after this procedure.