Remember that this uses PresentMon, which is an open source tool.
Nvidia's secret sauce is the power stuff. Don't trust that if you don't want to. I certainly won't, especially when it is used to compare GPUs across vendors.
I'm going to have a look at this over the next few days and see how good it is. To be honest it doesn't take much to beat presentmon in its raw state. Even AMD's Open Source OCAT isn't great.