Yes, those are the CD4E caps. C4DEHPQ6150A8TK to be exact. The thought was more along the lines of package and stray resistance (voltage spikes). The literature I've seen shows the arrangement I have as the most ideal for further reduction of stray resistance, with the two parallel copper plates attached to the bus bars. With three caps, it was possible to get them much closer to the IGBTs than the single cap. Of course, this has yet to be proven. To date I've tested it up to 70 volts and 20-25 battery amps and have seen in the ballpark of 15v spikes. The spikes so far have not changed with higher current (0-25 amps gives the same spike), so I don't know what will happen when I go into the hundreds of amps. I've also so far done nothing with the gate resistors to improve anything. I just started simple with a 5 ohm turn on and off resistance. For more info on the build and testing, check out my blog:
Porsche 924 Electric Conversion