[Speedslug]

Also if I get too excited I tend to pull the bead in too close to the torch face where the fuel has not burned up yet and I get soot on the glass.

Took me a some months to break that habit ( and I still have trouble with sometimes).

Someone told me Anise White was really good at showing soot so I had thought I would use it to check for a neutral mix of fuel and oxygen.
Then I could tweak the mix one way or the other to get an oxidizing or reducing flame..
I have not gotten any yet to play with but it's an idea.

Devardi is known to be a less expensive glass and you may well find that the batch of any one color you have right now could behave very different from the next batch you get, so that could be adding to your troubles too.