Rear LED light effectiveness.

Driving home last night I overtook a cyclist with what from about 100m
away I thought was a very dim constant rear light. As I overtook him I
saw it was a Cateye LD600 on the chasing mode where each LED lights up
in turn but there is only one LED on at any time. So from the
perspective of a driver this mode would appear to be useless. IE only 1
fifth of the light put out compared to either the constant mode where
all LEDs are lit or the flashing mode where all LEDs flash
simultaneously. Plus from a distance the chasing mode loses the
flashing effect.
I use two LD600s on my commuter but don't use the chasing mode anyway.
But it made me wonder whether anyone knew of any side by side
comparisons of LED lights. Given sites like "Your Tube" and Google
Video it would be possible to post video clips of different lights "in
action" so to speak, perhaps side by side comparisons.
As a side issue the cyclist concerned had a poor rear light, no
reflectors and dark clothing. But he was wearing a helmet so
everything would be OK right?

Iain