So far in my experience, I find that if you have the vision of how it should be in your mind, direct and run one of the cameras, and get the shots exactly as you wanted. This has for me been the best way to do things, as none of what I have done so far has been scripted nor storyboarded, just planned out on the spot. Course, if it's actually scripted and storyboarded, then it is easier to get the shots you want, relying on others to run the cameras, but it still may require some extra direction, especially if you are aiming for modern cinematic moving camera techniques, some people are not going to get the camera movement right at first, may take a while, and sometimes, time is terribly limited.
In my latest video,
The Hall of Wrath, things were rather complicated. Normally I'd be the cameraperson and director, but this time, there was no one available to act with the other guy, but several willing to run cameras. It was very very difficult to get the shots I wanted them to get of us sometimes, I felt like a complete n00b at directing, but in the end it came out decently, though I would have wanted, had we more time, to get some much closer in, Bourne Ultimatum style shots, but I'll handle that in one of the next ones. I actually did grab the camera and do some shots that didn't need me in the frame myself, to speed things along (like the shots moving from a close-up of the guy, to the close-up of the gun, and reverse, and the shots of the girls coming in at the end, which in fact, no one else involved was there, yet it worked, as I had directed the camerapeople to shoot us in ways that wouldn't require the girls to be in frame.
The point is, there are many of us who just can't really call ourselves just a cameraperson or director, but filmmaker, as we may have to fill in several roles on low budgets. Even on a high budget and large crew, I'd still prefer running a camera as I direct, it's just what works best for me, though I would like to strictly direct once in a while to actually teach modern techniques.