TAv mode — do you use it?

I agree with you that the lowest possible ISO value is almost always the most desirable. To me that's an argument for using TAv: Selection of ISO value is a no brainer, and therefore the variable best left for the camera to descide. It can safely assume that this value should be as low as possible. Not so with shutter speed and aperture.

I think TAv can be useful in any light. Let's say you do street shooting on a sunny day. You want a shutter speed of 500 to freeze motion and ensure sharpness and an aperture of 11 for good DOF. TAv could then be very handy. Of course you should still watch the exposure and the ISO, but you wouldn't have to be changing the ISO manually all the time.

I'm much more comfortable with letting the camera control ISO (within user defined limits) than either shutter speed or aperture. Jay Maisel supposedly leavs his ISO at 1600 all the time for cinvenience since he thinks it's "good enough".