If you communicate with a lot of different people, I'm not so sure how useful people contexts are, unless you really want to start getting a super long list of contexts (which I've tried to avoid, because it can get overwhelming).
That being said, whether it's the same action or a new one I create (or previously created as a part of a project template I've made to use with Curt Clifton's Template AS), I use the waiting for context to create a blocking action in a sequential project. That's typically a pretty good signal that something needs attention.
To me, it makes more sense to think about things in terms of a particular action step (review what kind of stuff I've got outstanding with various people), than it does to think about it in terms of a particular person.
But that bias probably relates to the realities of my workflow. If I had less than 10 people that I typically was sending and receiving things from, centering contexts around people would probably feel a lot more useful to me. But since I don't, I tend to focus on either the project unit or the tasks under a particular context unit (e.g, computer off-line, waiting for, etc).
There are some Applescripts in the extras area of the forum that are aimed at helping to streamline some of this stuff in OF (e.g., Comp and Await Reply).
But honestly, the real key to this, and I think GTD in general, is doing regular reviews. If you don't do that, it won't matter what your taxonomy of contexts looks like.
And remember, while OF may be your trusted box for a lot of stuff, it doesn't need to be your trusted box for everything. If you find it more efficient to put certain stuff in a different sort of box, I don't think doing that will violate some sacred canon of GTD.
That being said, if you use more than one box, you need to make sure that your weekly review involves looking in each of your chosen boxes. Also, the more boxes you have, the more likely things may fall through the cracks. So each time you decide to add a new box, make sure you are convinced that the efficiency benefit outweighs the possibility of losing something.
I tried to keep track of everything in OF for a while. But what I have mostly ended up doing is moving e-mail tracking out of OF (unless it requires a major chunk of work, like writing a long e-mail that will take 30 minutes to draft).
Lately, I mostly manage e-mail exchanges with labels in gmail. Even using mailplane, which has OF integration in it, I found the relationship between OF and my e-mail less than graceful. For me, it's proven to be more hassle than it was worth. Maybe if I used mail.app it would be better.
Instead, what I do is create an Awaiting Reply label in gmail (AR). I also configured gmail, so that it will automatically apply this label to any outgoing message I send that contains a signature line with a special sequence of symbols at the end. Then I can apply this signature very quickly using the gmail canned responses lab.
When I want to review what e-mail is outstanding, I just search for the AR label and I can see them all there in one place. I also use the multiple inboxes lab of gmail, which allows me to see AR labelled messages underneath my inbox. I also have a label called "needs action" that I apply to messages that need a response, but will take me more than 2 minutes to complete. In some cases, I'll also add a needs action e-mail to OF as a task under a project. But often I don't.
So for me, OF often functions more like the project tracking command center, where I can keep track of where a particular project workflow stands. But I may not be tracking all of the micro-steps in there.
Everyone's workflow is different, though. A lot of my projects have similar workflows that I have distilled into templates. That way, I have a checklist in OF to work off of, so I don't forget important steps (e.g., gather client information, send engagement agreement, receive, engagement agreement, make client file, etc).
That book the "Checklist Manifesto" influenced my thinking around this to a large degree. It took some time to build the templates. But over the long haul they have speeded up a lot of stuff, and they also prevent me from forgetting important steps, because I'm not reinventing the checklist in my mind each time I start a certain sort of project.
For me, OF is a great help in making sure that I follow my flow each time I begin a certain sort of project. That way, if a project gets put down for a few weeks, it's easy to review the project in OF and quickly remind myself where it stands. Usually, doing that also provides me enough context to look at my AR and NA e-mail labels in gmail and find any hanging chads there.
Not sure if that's helpful, but it's what I've settled on after using OF since it was the Kinkless GTD template for OmniOutliner (Is that 5 or 6 years now? I can't remember).