It will be a huge help to have offset setup with "unwrap" function per pixel.
Now we have "Margin" option, it's work on some value from 0 to 1. It's very hard to predict how big distance between to UV shells.
Also if we have different size of map (512x512, 1024x1024, 4096x4096) - value from 0 to 1 make more confusions.
What I propose - make the option when you can set distance between UV shells by pixel.
It will be more predictable and understandable.