There's a precision adder in the Disting. Joranalogue also makes one that's pretty tasty.

With buffered mults, in an ideal world, you want multiple copies of EXACTLY what you've fed into it. Being able to attenuate or boost the outputs would defeat the purpose of a well made mult. Your buffered mults will serve you well when you're trying to split the same control voltages... especially those controlling the pitch of two or more oscillators. Passive mults or simply splitting (like with a stackable cable) can cause voltage drops. A drop in voltage means you're not getting the exact CV that you've put into it.