if it works, then an exp object is perfect, sure. by looking at the code of the vca object you can see that it interpolates the blue signal over the 16 times faster red signal, so the volume changes will be smoother then with a multiplication object where it just uses 16 times the same signal to calculate the gain.
generally red cables are calculated 16 times the speed of control rate (all other cable colors).
control rate: 3000 times a second
samplerate: 16x3000 = 48000 which equals of course axolotis samplerate