Also note undervolting too much can cause crashes, system instability and corrupt data. Bear this in mind if using XLV ULV and Starving especially at lower frequencies.
SR seems to work nice for me at the moment on KP.

The idea behind the 500Mhz in ideal AFAIK...
..is the process is done quicker and the system hits idle quicker.
Saving battery in the process. I would think it depends on your usage, tho.