Closing Active Connections sooner for maintenance

Yeah I was reading about the LB_SELECTED event last night and thought it would be a better event to respond to. I am now curious as to what the "reject" actually does. Does it kill the request and give the client an error? Does it complete the request and then kill the connection? Or does it just force a reselect? The Action on Service Down does sound like the best approach if it works like I hope. Does it mean when the actual service (IIS) is down or when I disable the node or pool member in F5? I have to avoid client errors like the plague and each request still needs procesed.