I have both an umbrella and a Chimera. Which one I use depends on how much control I need of the light.
If I'm in a big open space like in a theatre, or if I want some spill; I shoot the light through the umbrella because I like the light quality better. If I need more control, I use the Chimera. The grid is nice, but not totally necessary. If your subject wears glasses, use the Chimera because if you catch a reflection, you'll see the spines of the umbrella in it.
One of the big problems with umbrellas is that they're pretty fragile. They break by wearing out from normal use.
I've had a lot of practice, and our Chimeras are well worn in, so it takes me less than a minute to set one up.
I carry two Lowel Pro lights (250 W)and an extra stand for a reflector. A nice set up is the umrella as key, the Chimera for a hair light, and the refector for fill. My kit only weighs ~15 lbs and is very compact so I get no complaints about carrying it.
[ July 28, 2004, 03:11 AM: Message edited by: 2000lux ]