The short answer to save you having to decode the soln note :) is that unless it's a fastL4 connection, then the BigIP acts as a full proxy. The original tcp connection is terminated in tim and then tim opens a new one. When tim opens a new one, it can hide its own connection by default with YOUR IP address and port as the source, or using one of its own address (SNAT).
The target IP for the connection is the pool member ip:port, but you can disable NAT on the VS and have the pool member used as a router to the VS address (n-path).
H