A Question About Double Sides

[LHawes]

I've read and viewed many an opinion on the theoretical benefits of using double sides and understand one theory that suggests that stiffer sides allow the top to vibrate without losing energy through the sides similar to a drum head.

What I was wondering is what do double sides do to the tonal properties and tonal contributions of the sides? For example if a guitar had BRW back and sides could one safely assume that some of the tonal quality of that guitar is going to come from the BRW? From both the back AND sides? And if the sides do contribute to the tonal characteristics of the guitar what does doubling the sides change in that equation?

And to expand on that a bit further, what happens to the tone when a BRW side is doubled with an EIR side? Are the tonal contributions of the BRW negated to some degree? Completely? Or do the sides contribute so little to the overall tone that doubling a BRW side makes very little tonal difference and the (theoretical) benefits of a double side outweigh any negative impact that the EIR doubled side might have on the BRW side?