Regarding the second diagram, Again I think it looks great. The User icon (although its already pretty obvious) could have a label like the others.
Also, I'm not sure the little arrows between client/passive STS are descriptive. AFAIK, the User communicates with the TraderClient/Passive STS independently and there is no actually communication between the TraderClient and the Passive STS. I'm not sure if this was the metaphor you were going with, but this may be a stumbling point for users. No need to change this, I'm just curious about others thoughts on this. -Ben Dewey
