The driver wires are closer to the edge and thus probably better heatsinked than the LED. The real issue with 3-4A of current heatsinked through just a PCB is not just potential desoldering, but the rapid loss of performance and premature emitter death. LEDs performance is already very sensitive to whether the board is made of Cu or Al; removing the heatsink will make a much, much bigger difference than changing Cu to Al.