If you change the flash power, remember to check the next few shots carefully, are you getting flash sync errors, has the colour temp changed so do you need to do a fresh white balance. Its not just getting the exposure right.
When I am using studios with cheaper flash heads I often need to check these things or lose shots.
When you can shoot tethered it does make it easier to spot if things have changed.
When on location as in the shot above of the lovely Ivory Flame, I was mixing changing daylight with flash, in this situation having a flash you know you can rely on is definitely and advantage.
