The 3000 v 6500 is the "color temperature", or some see it as "warmth" of the color. Some LEDs emit a fairly white/blue whereas some are more yellow like the sun's natural color. It has nothing to do with power really. The 70 Lumen spec is directly related to the amount of light emitted and other than efficiency, that is the real factor in determining power requirements. You could put smaller (Lumen rating) LEds in that fixture by replacing them on that board without too much risk, but not likely much higher rating LEDs. You will notice some active components on that board. Those are designed to regulate both the voltage and the current that drives the LEDs. I would imagine there is very little overhead in the circuit design and construction, like John said. But if all you wanted to do is change the color, but stay with the 70 Lumen output, you should be able to get away with that.