Wattage is irrelevant to the amount of light output from LED's and even for the old tungsten lamps. An inefficient driver is going to take more current and produce less light. A higher Wattage tungsten lamp is going to be more efficient so a single 150 Watt lamp provides considerably more light than two 75 Watt lamps.
Electronic devices do not do well with heat and heat sinks are only a partial solution if the fixture itself does not provide for air flow around it. It is why CFL bulbs when used with the driver on the top (as with a recessed can fixture) will fail much more quickly.
I focus more on the color temp which varies widely with the different LED's being manufactured. The higher the Kelvin rating the closer it is to approximating sunlight.
