Please note the write-up on the bottom of the opening post in this thread: https://budgetlightforum.com/t/-/16621 by Match. He's saying there's very little difference in results between a SinkPAD and a large copper milled PCB. This is a very meaningfuil quote from Match:
"I'll let the data speak for itself, but suffice to say that with the availability of these sinkpads, I've milled my last copper pcb"
This doesn't mean we don't need additional mass and heat sinking, but the direct bonding days seem to be over. I'll typically go to 3.85A in a C8 sized pill, but this is with adding copper inside the pill, and expecting short duration runs on high, upt to 6-7 minutes, from my testing. 4.2A amps I go with in lights like an HD 2010 or Small Sun T08 - those bigger sized lights, but thinking could push it higher still to 4.5A maybe, taking into account switches, spring wiring, heavier LED wiring, etc.