it's to do with how we perceive loudness... our brains work exponentially...
so linear is usually for cv and exponential for audio...
althoug it also depends on the envelope that you feed them... an expenential envelope into a linear vca will behave in the same way as an exponential vca...
personally I'd get a veils clone instead (even if it means waiting a short while before buying it) - does both linear and exponential + loads more interesting features + more channels - which is always good (you can never have e nough vcas) and probably cheaper per channel!
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities