Not sure for an overall change, but one thing I found when adding white flashers to the red saucers on AFM was that the result was slightly orange, and not nearly as red as I would like. Almost as if the intense light washes the colour out a bit.  Haven't tried reds yet to see the result though, so don't know if will be any better.

I guess if RED leds aren't an exact shade of red, you can always wrap a white led with red 'lighting gel'
(it's a thick coloured film (like non-adhesive mylar, basically a hi-temp version of 'cellophane' we all played with in primary school).
Lighting gel is available in a range of shades for the fussiest colour-matcher on the pinnies ;-)

MM.