Even with a 1.4 lens, I'll not be using it at 1.4 to track action.
I'll want to set the appropriate aperture to maximise my keeper rate.
Why set yourself up for failure?
.... f1.4 apsc is around f2 in ff. i shoot f1.4 in ff quite often... it is all about the look of the pic you want. if a camera forces me to shoot at a smaller aperture due to the limitations of its af, i guess there is still room for improvement