re the Lumiquest diffuser (and teh many simlar devices on the market), while these devices will slightly diffuse the flash, the amount of diffusion is quite minimal, in my experience. Plus they also cut down on the amount of light that will reach the subject, so for light output its probably a draw between those and the Lightscoop. However, the Lumiquest-type diffusers are still aiming the flash directly at the subject, so all the disadvantages (shadows behind the subject, etc) are still present. The Lightscoop would avoid those issues. Bottom line is the two products will provide a very different look, and the odds are the Lightscoop will tend to produce a more flattering result. No, it won't be a match for a good flash unit, but in a pinch or the right situation it could be highly useful. Might be a handly little thing to throw into the bag.
jZ
"High Key" is NOT overexposed, and "Low Key" is NOT underexposed.