I have found through testing that with anything but the very high end Profoto and Broncolor packs, 1/250s is as fast as you can go with out loosing light at high power. (BTW, I use a tech camera with Copal shutters.) The reason for this is because the flash duration at the high powers for most strobes is slower than 1/500s. The main burst of power does happen within that initial 1/500s, but the flash tube still emits light afterwards as it drains out the power. (The tube goes from dark to as bright as it can get super fast, but dims down more gradually.) By 1/250s, all of the light is emitted (at least for the Pro Acute packs.)
For me, this does not matter since I always shoot things that do not move. I tested this more to see if I ever shot products in a studio with windows, could I shoot fast enough so the sun had no effect.
However, for my girlfriend, who shoots food and drink, the Acutes are just not enough for splash shots. For this, the Pro 8as or the high end Broncolor are the way to go to get flash durations shorter than 1/500s. But, even with these, you are cutting it close. I believe at full power, the 2400 ws Pro 8 has a flash duration that is only very slightly shorter than 1/500s. You really need to decrease power to get flash durations less than 1/1000s.
Insofar as transmitters, I have found that Pocket Wizards works with 1/500s.