My situation was different because I had to repair my subframe and I was going for full penetration. For stitching its obvious the gas shielding is better. I did a bit of stiching but nowhere near what you did but I didnt have shielding gas so I wasnt able to get as technical with it. Im still in need of a tank. Ive seen some very nice TIG welding and they get very good penetration.
Here is some good reading.
http://www.millerwelds.com/resources...wire-selection
That came out very good btw.