For standard def work on a nice quick G5, shake performs pretty well. I've actually had quite a few clients and agency folks used to flame suites comment on how fast it was. Especially if they are used to a facility with an older sgi box.
Then you hit render and there is no spinning wheel or rendering graphic on the monitor and suddenly they start saying it's slow, even though they then say the render was quicker than on a flame!
I'm putting a desktop image on my broadcast monitor that has a cool graphic that says processing now.
Cheers,
Toby