We use it to store atlased paths at the moment and it produces much better results.
As far as format, we use an 8-bit 3.5 fixed point format, because it allows us to combine the SDF and bitmap glyphs into the same atlas to conserve space. There is a sacrifice in quality, but we only use the SDFs for larger glyphs so it's acceptable.
If you would like more details on our implementation please let me know. I'm looking forward to seeing how this turns out.