I want to see the total number of frames.
I've noticed the FPS is somewhat pointless because after some time the framerate goes WAY down.
I'd rather leave it for a certain amount of time, see if that number of frames is what I want, then attempt to use that for rendering.
Also, how about lapsed time since last change? With both of that information we could probably give ourselves a good estimate on what the render quality for a particular image is.
Just as an example, my computer just went from 8:12 to 9:31. Hmm, not the greatest framerate, but the real-time at only a few frames says 1.9 frames per second. Not 1.5 minutes!