Now, You are pretty much guaranteed to win you know that. I saw something like that in a magazine with a quarter dropped into water. So if you lower the flash power it drops the length of the flash, and you can still have it timed right. (as in the flash sync)I will have to try that.
I too was wondering about the amount of flashes. I have done some experiments with this type of image before and seem to always struggle getting enough light while at the same time ensuring the flash duration is quick enough to freeze the motion of liquid, falling objects, etc. Is it simply a matter of multiplying the number of flash units? Is this better suited to a actual studio flash versus using speed lights? I haven't compared them as I've always used speed lights for their portability but maybe the studio flash is better since it is stronger even at quick durations? Thanks!