I've heard and read that the powder blocks up the stems. Not sure, I've used both with success. Likewise I've had 100%success without using any hormone whatsoever.
With clones it's about the environment you put them in.
Young cuttings have a lot of work to do as their system for gathering water (the roots) is gone. Heat, low humidity and intense light all create demands on the cutting's water supplies. When the demands are greater than the stems capacity to cope the leaves wilt, although once you get the environment right even wilted clones can pick back up again after a few hours.
The amount of leaf you leave on your cutting is also very important. Less leaf, the faster it is to root. If you have a large fan leaf, and you don't want to remove it entirely then you can just break bits off it, giving it the appearance that a voracious caterpillar had been at work.
Light is also very important in regards to how long you have it on for and intensity. On an 18/6 schedule your clones will only produce 75% of the sugars, the tissue building blocks, than it would under 24 hour light. For fastest root growth it's recommended you have the light on them continuously.