We have experimented with it but never put in into production
We ran quite a bit of 95 Ar - 5 O2 in the early 70's spray arc on steel
ran it very sucessfully
Structural shop I worked in ran exclusively 95/5. No problems. Wets well. Very well. Nice fluid puddle. Never had any trouble with UT's on CJP splices. Issues with impact testing and siesmic though. Not insurmountable but retesting is necessary.
I've seen it, especially 95/5. Depends on application.