My local office is responding to my emails (there's a backstory there), so I got this regarding the Gold Settlement service:
There is a slight benefit in expected processing time with the Gold Settlement service when compared to the Priority service. However, the largest benefit is the input of our staff, who can review the supporting documents an applicant plans to send, and advise if there are any absent which should be provided with your application according to guidance from the consulate. As you have likely discovered, getting such input can be challenging when it comes to visa services, and some of our clients rely upon our assistance.
Not exactly a firm commitment to faster than normal priority processing, but there's also the coaching piece, which they refused to do before. I'm confident this forum has even better advice, but not everyone discovers this forum...