I'm worried to answer the question about manageability. As far as I am aware, manageability is related to the management of available resources on the application server such as security, concurrency control and resource management as polling object and so on.
I believe it have nothing I can do in the solution architecture that can provide "greater manageability". Only use these resources available in AS as datasource pooling, pooling stateless, etc..
How could I answer the question of manageability