I just went out yesterday and bought a gas lense set-up for my 200I, and I think it has made quite a nice improvement. My TIG skills are pretty shaky at best so far, but the gas lense did seem to help quite a bit. I was also expecting to get a glass nozzle, but the "Air Liquide" shop here in Saskatoon doesn't stock them, and told me that Hitachi Industries, who build large wind turbines here tried them, and found them un-necessary, and a bit pricey.
I tried to get a picture of the trial but-joint I did on 3/16" steel, but for some reason couldn't get a decent shot. - - Just as well, my Tigging still isn't beautiful, but the new lense did seem to help quite a bit. the gas distribution does seem to be quite a bit better, and the arc smoother.
The whole set-up including two collets and two cups cost just over $30cdn..
If anyone wants a picture of the parts required for conversion, let me know and I'll take some.