Interestingly, I was playing with SR a few days ago.

It worked for me with 500-805 MHz, but I found when watching a video there would be high-pitched 'squeaks' every 20-30 seconds. I was worried that these squeaks, presumably miscalculations/operations failing due to lack of voltage, would translate into file corruption over time.

I also tried it with another power kernel profile with the same speeds but at higher voltages and there got instant reboots. So if you suffer reboots and want to try, see if you can reduce the voltages in your kernel-power config.