Update:
The good
It definitely gets to welding temp. Had a job come in to bend some 1" diameter 303 stainless at 90 degrees. Wasn't sure I could do it with the bender I have so I tested it with some 4140. Cut three pieces to 13" long and put them in the forge then lit it up. Took about 15-20 minutes to bring them to what I call bright orange. When I went to pull the first piece out it was stuck to the mild steel rack that I use to keep the stock off the forge floor. After getting it unstuck and out of the forge I noticed that it was sparking just a little bit, which I believe is one of the ways to tell when steel is hot enough to forge weld.
The bad
This was the third time the forge has been run for an extended amount of time. It has destroyed (burned through, melted etc.) the stainless insert and the 2600˚ fire brick floor has a good size hole melted about half way through under each burner. The brick is a little over 1" thick.
So, do I drop the coin on some higher temp rated bricks or just keep a few of the 2600 on hand and just replace them as needed?
Anyway, the job was completed and the customer was more than happy with the pieces.