@Pete - not sure, but I wouldn't be surprised if you could get something working in a similar manner.
@newbie - Only for OWA (ECP is generally accessed through OWA). It is not required, just useful for the scenario described, and will be a best practice for that scenario. Pros and Cons? No Con - it is only called upon in the scenario described. Pro? You don't get into the looping scenario described if you use it. ;*)
Note: All of the implementation details and functionality described will be tested and demonstrate as we get to the implementation portion of this blog series. Right now, we are still just planning the environment, talking through the decisions needed to fully implement Exchange. I'm as impatient as all of you readers - I'm ready to start building servers! But, we have some groundwork to cover first. Trust me, we'll get there and I hope to cover all of these implementation questions then!
Thanks again for reading! Great questions!!