I have the Lumiquest 80-20 and the Stofen Omnibounce and I use the Omnibouce 99% of the time. With the Stofen you can still bounce and diffuse off a ceiling in portrait mode, while the Lumiquest does not allow you to bounce as effectively. The built in card really isn't too bad for landscape mode as you already know.


The problem with most of these diffusers is that in portrait mode, you still create a side shadow behind your subject, whereas a bracket mounted flash with a diffuser will generally keep shadows straight behind your subject (and more likely less distracting).


I like the Stofen also because it is the least distracting of the different diffusers--but it will be a moot point once I finally get around to buying a bracket!


The Omnibounce is so cheap you can try it without too much guilt if you don't like it. I would definately recommend some type of diffuser though, it really does make a world of difference in flash photography.