If you wondered what is the maximum amount of data that can be sent through the bus or what are the maximum pds size recommendations, here is an interesting piece of information:
The average qos metric on the bus is 600 bytes. Optimal posting bulk size for the hub spooler is around 2000-5000 qos per send, so we should be fine up to at least (3000 x 600) = 1,800,000 bytes per send. Callback replies should be as short as possible. With the latest version of hub there are no limits at all on PDS size. Discovery occasionally sends data well over 10Mb, but not at sustained rate.