I haven't tried that, but have tried various shoulder braces.

If your shoulder's are slumped forward, it is because of a tight pec minor. Find your pec minor muscles and massage them (or get them botoxed). Also, do wall pushups to strengthen the rhomboids and deltoids.

I had the pec minor release surgery without the first rib resection and scalenectomy, but it along was not effective for my cause, but I think it has been for some people....