I'm running the Quark on 4s with a 2600kv Neu on my buggy and it runs cool with a simple small heatsink (no internal mods yet). The internal mod just makes it run that much cooler.
And just to clarify about the way the internal pads work and what needs to be done to replace the existing heat spreader:
The drawing above isn't exactly to scale, but you get the idea...
The stock heat spreader is 2mm thick and each pad is 0.5mm thick. This thickness is needed so the capacitors clear the case. Once you remove the pads, there isn't enough thickness for the caps since the epoxy is very thin (practically 0mm). So, a new spreader that is 1/8" thick works perfectly.