I am happy with it too, but you know how it is, when you get something new you maybe hope it may do the 1/3 stops of 1/640 and 1/800
It is only a minimum - so in bright light I am often much faster
Dont forget you can dial in min/max ISO too - again full stops. My 1D4 is set for L/6400
Another alternative is to set the Safety shift to TV/AV and shoot on TV
In Tv mode, the Tv/Av Safety Shift behaves the same way only changing the shutter speed instead. For a required exposure of f/1.4 at 1/250th with a lens that can only open up to f/2.8, Safety Shift would cause the camera to drop the shutter speed to 1/60th to insure a proper exposure. Alternatively, an exposure that required an aperture smaller than the lens could produce would result in shortening the shutter speed until the exposure was correct. With Autoiso set then this only shifts when the ISO limit is reached.
This gives you the fine control over the shutter speed