If I understand correctly you basically use the model light and catch it before it goes (if its Profoto 7b-2 seconds) and you get a less powerful light than the flash from the strobe. I do that sometimes when im happy with the light i can see from model light- but its deceptive because as we all know your eye tricks you into thinking its brighter than it really is so bracket (if you shoot with film)
Will look dark and moody.
Maybe i misunderstood the question?