I have some old sodium halide lights in my back yard and in the front I have three wall mount lights with fluorescent bulbs set up on a motion detector.
Mine have lasted over a year now since I switched but they are not standard motion lights. These are regular porch lights that have been wired to a motion switch.
I have three or four more. I will go out and look at the bulbs to see what they draw but I never noticed a difference on my bill but I only run one in my tiny yard here. I saved them from a job where I had to pull out about 50 of them from a christmas tree lot.
I had to start using a flourescent bulb because any kind of motion could rattle the regular bulb and make the light go out by breaking the wires inside