The latest release of firmware for the Pocket Wizard ControlTL system supports Nissin Di566 flash.
There is an article on Rob Galbraith (sp?) site describing how they worked with beta firmware.
My experience with Quantum T5Drs and Turbo batteries was favorable as off camera flash.
The Turbo batteries recycle a 580EX or 580EXII at about the same rate as a Canon or knock-off 8 AA pack with NiMH batteries.
I quit using and sold my Quantum gear and now use the Control TL stuff with 580EX and 580EXII Speedlites.
A 580EXII, AC7 mount and battery pack on a nano stand is a nice, compact off camera light source that can be used in manual or ETTL mode and controlled with an AC3 on the camera.
If one were to use the Nissin Di566 the total price would be less than the Quantum by a lot.
The Quantum is more powerful but Its rare when the 580EX is firing at full power.
As for the Zumbrella; It and the collapsible Westcott are essentially the same. Ziser claims his lets more light trough. Again, when I had a Zumbrella it worked fine, but when it got wrecked in a blow over, I decided to get the Westcott version. Less than half the price and it works fine.