Subscribing to this for more suggestions. I tried your suggestion Jeff, and while it didn't do the squiggly lines or anything, it didn't work.
Tried using it in the 'Change Score' field directly, and it told me I needed a whole number.
My workaround so far is to setup a whole bunch of If statements. Here goes:
My demographics can never get higher than 15, so I have 15 IF statements set up in the flow step.
Flow Step 1: Change Behavioral Score = 0
Flow Step 2: If Demographics Score = 1, Then change Lead Score = 1
If Demographics Score = 2, Then change Lead Score = 2
so on up until 15.
The default I have set up is Change Lead Score + 0.