Chip, I wouldn't say everyone, cause I am someone.... :)
Oz... Icicle is one of the most carnage inducing rivers that I know of in the state. I've seen more swims on this one particular river than any other put together. Not to say that there aren't other rivers that are harder, but just that the Icicle has the niche for being roadside class IV-V and is more continous than many runs.
My suggestion for you is to start with the lower. GO with someone who is willing to take the time to show you whats where, which on the lower is pretty straight forward. IF that tickles you pink, then go to the upper (roadside-limbo), its a notch up in difficulty.