I agree with nightshark. Over the years, I’ve tried many brands and they have all been horrible. Unreliable, prone to failure when used in enclosed fixtures like the glass carriage lights by the front door, highly variable performance re ambient light levels. Just junk. This is irregardless of incan, fluorescent, or LED.
Wilkey
The problem is most CFL’s and LED’s are not pure resistive loads (incandescent lamps are essentially pure resistive loads). These devices have ballasts or power supplies and often have a low power factor, so the current through the dusk to dawn light bulb adapter can be much higher than the wattage of the lamp would suggest. This often causes premature failure of the adapter. While it is possible to build these devices with power factor near 1, it costs money to do so, and unless you are a commercial user electricity, there is no penalty from the power company for low power factor devices. Since there is no penalty for residential users, there is no incentive for them to pay extra for a high power factor devices. Since there is no incentive to buy such devices, there is no market to build them either.
I’ve had similar problems using X10 switches to operate 70 watt HPS fixtures. The switches are typically rated 300 watts or more, but they don’t last very long because the typical low cost 70watt HPS magnetic ballast has a low power factor.