In general, I would agree on most of the comments. 2 operators are optimal along with shooting on the same axis for lighting purposes. Also, yes the two camera's may have some slight color shifts, but nothing a DI can't handle. Having said that, with the proper location choices, two camera facing opposite direction can be worthwhile and save quite a bit of time. I shot a film called "Think Like a Man" that had a 33 day shooting schedule with a 140 pg script. Lots of dialogue in restaurants, clubs..etc. Most of it being two actors facing each other. By making sure the actors sat next to windows I was able to light both actors at the same time...while using slightly longer lenses to keep the camera's out of view. In all cases, the windows we're also next to pillars which I utilized to hide the lights. Each actors "key" light was also a soft backlight for the other. In one particular scene, I used 3 cameras. I had a 50-50 along with over over's on each actor. The 50-50 was interesting only because it was "front lit"....but when you have very soft front light and a deep background that falls off (back of the restaurant) it can be visually appealing. FYI.. It worked well on that particular film because we planned it out in prep. The director and I collaborated on locations based on our ability to be able to shoot in opposite directions...but in general, without that kind of commitment in prep, stay with the same axis.