Ducking the music bed behind voiceover work gets done on my end almost daily.
Sounds a hell of a lot more pro than just turning down the bed when the voiceover comes in.
I strap a compressor across the music bed and key the sidechain input of the voice track. Simple stuff but effective. Pretty standard stuff really.
Now if only my boss would invest in some decent analogue compressors.
I routinely use my API 225 for ducking. I'll send a kick mic to the compressor, then sidechain in the snare. That way I can get all the snare bleed out of that mic with out using a gate. Works the other direction too.
In fact, I'm wondering if there are any cheap compressors that I should try this with instead of using one of my best comps for this purpose.