CerinoDevoti:
The putter scale can be adjusted and there's a product in the Pro Shop called Putter Pal. It's a visual scale exactly like you mentioned.
What you say! I use the mouse wheel to adjust to my liking.
Plus, the putter scales are linear from 5 to 100 %, only green speeds and break influence may vary :)
One putting tip which I grabbed here is to choose a bigger scale than necessary, because the meter will run slower on short distances. I've become used to pulling only env. 40 % of the scale, otherwise I tend to check the next available scale (15, 30, 60, 90, 150, 300 on my Daytona Rossa). Alas, from the 150' scale on each two percents are a critical length variation :)