I have shown C rate test data before that proves our cells keep 90% of there rated capacity at full C discharge. Here is the info again for those who haven't seen it before.
I recently purchased equipment that will allow me to discharge up to 250 amps so I can test packs for C rate. I'm very busy at the moment but it's on my to do list as I have a feeling many companies have been using inflated C rates. They know it's pretty hard for the average guy to test for C rate as it requires a discharge setup that must do high watts which isn't cheap.