The F4 VR III should be o.k. in a studio setting where everyone shoots F8. For any sporting events - you will need the F2.8 VR II.
It is not just F stop. For example, the mechanism enables the 70-200mm F2.8 VR II focus a lot faster than the 85mm 1.4 G AF-S.
Did not use 70-200mm VR I, can't comment on it.