Wayne dropped me a line and asked me to post this. It's the data from when I tested the C's with heatsinks. I now have a new Fluke and should probably redo them. But this was enough along with the a's test to convince me. This test only went to 10 volts as I fried my resistor. I tested with the a's to 30volts.
Contrary to some opinions, these things work, and work well. I routinely run 400-500w average through my 300w rated c's, with no ill effect.