I'd like to rise the suggestion again to have some more control over the load-balanced backends.
E.g. to give some priority number or something in the load-balancer configuration to send more requests to a given backend-server which can handle quite some more load.
Yes, you can have one backend server handle more requests, by raising the "Max connection" for that external application, load distribution is based on the ratio of "In use connection"/"max connection".