>Do the black :-) LEDs consume less power

Don´t think so.
The infra-red LEDs (as used in remote controls) seem to be black. But I
don´t see the point in using them in a modular ;-)

>What do the VU meters on typical mixing desks usually show

VUs show average as the mechanics move too slow. One can say it
simulates the human ear, as we hear the average signal, not the peak.

best,
Paul