As I work directly with growers at origin, I do not go through a broker. However I would expect as they are professionals and their business depends on roasters coming back to them- that they would offer as much advice as possible. The brokers I know in the US are true professionals, some even with roasting experience. However I am not sure this is the norm elsewhere...I know a lot of European brokers who do not have roasting experience at all. In the European case the brokers rely on feedback from their big roasting clients rather than the other way around.
My guess is that the future of brokers in the business should be that they can offer not just basic advice on the greens the offer- but also comprehensive origin information to their clientale- including traceability, photos, geographical information, plant type (specific type of Arabica plant the green is from etc).