Many LEDs do have a dominant wavelength change with respect to
current, and, as you say, at some wavelengths, this can have a
significant effect on their visibility.
The main reason I mention this is that it's important to be aware of
possible ways by which an apparent brightness change might occur.
Otherwise, in ignorance, all manner of random guesses about it might
be supported by apocryphal observations. I'm in full agreement with
your general points here on the subject, but knew of a few details
that might explain an authoritative source for argument.
In any case, if those disagreeing with you intend to say that the
human eye is some kind of peak detector, they need to show this
through both theory and experimental result. On theory, I don't know
of a mechanism by which 'peak detection' would be selected in human
perception -- and given that what would in fact _be_ selected for is
the ability to see over a very wide range of lighting situations, from
no more than star light to broad daylight and specular reflections,
it's easy to understand why there is a rough log behavior in response
-- a linear system would be overwhelmed and useless or underwhelmed
and useless, most of the time. I see no reason for peak detection in
photopic vision. And given that some animals have acquired a tapetum
in their retina in order to enhance scopotic vision, I don't find much
argument for a mechanism there, either. Finally, I _have_ spent time
playing with various pulsing schemes and have found very little upon
which to base such 'peak detection' arguments, despite the perennial
rumors about it. It just doesn't seem to help one way or another.
Which made me wonder a little about wave-shifting effects, because it
doesn't take a lot of that in some cases to have an apparent change in
intensity perception. But I'm sure all this has been researched and
is available somewhere in the literature. I just haven't cared enough
about it in practice to go look it up. If anyone has citations to
some peer-reviewed science papers on the subject, I'd be interested.
Today, with so many
wavelengths to choose from, you might as well just select a device
that produces the desired wavelength.
And with the desired efficiency.
But this factor is something to be aware of.
Mostly in just being aware that there may be more than one source for
finding an apparent shift in brightness without changing the averaged
drive current. I don't think pushing wavelengths slightly factors
into much of anyone's design.
Jon