I have used a few different gas forges ( including those of a well known knife maker ) each with the burner angled to supposedly get the circulating flame, however it just creates a hot spot on one side of the forge and cooler spots elsewhere. I guess that can be useful? Although I tended to find it annoying with multiple bits of metal in there at one time I just built a gas forge an have the burner vertical as I figured That I'd rather heat the metal than just the side of the forge. But like Frosty said you need to experiment to see what you like.
Gees, thought I had more posts here than that... Sure of it, been a member since 2011.