Some info about the mercury in CFL bulbs from:
Compact Fluorescent Bulbs and Mercury: Reality Check - Popular Mechanics
How much mercury is contained in a CFL?
Each bulb contains an average of 5 milligrams of mercury, “which is just enough to cover a ballpoint pen tip,” says Leslie, associate director of the Lighting Research Center at Rensselaer. “Though it’s nothing to laugh at, unless you wipe up mercury [without gloves] and then lick your hand, you’re probably going to be okay.”
How much mercury do power plants emit to light a CFL?
"About 50 percent of the electricity produced in the U.S. is generated by coal-fired power plants. When coal burns to produce electricity, mercury naturally contained in the coal releases into the air. In 2006, coal-fired power plants produced 1,971 billion kilowatt hours (kwh) of electricity, emitting 50.7 tons of mercury into the air—the equivalent amount of mercury contained in more than 9 billion CFLs (the bulbs emit zero mercury when in use or being handled).
Approximately 0.0234 mg of mercury—plus carbon dioxide, sulfur dioxide and nitrogen oxide—releases into the air per 1 kwh of electricity that a coal-fired power plant generates. Over the 7500-hour average range of one CFL, then, a plant will emit 13.16 mg of mercury to sustain a 75-watt incandescent bulb but only 3.51 mg of mercury to sustain a 20-watt CFL (the lightning equivalent of a 75-watt traditional bulb). Even if the mercury contained in a CFL was directly released into the atmosphere, an incandescent would still contribute 4.65 more milligrams of mercury into the environment over its lifetime."
I am mystified by the variety of experiences with CFL's. Some people are happy and getting good results, others not so good. I can only think of several variables that might make a difference.
1) The bulb brand, model and quality control within the brand. There could be good and bad production batches coming from the same plant.
2) The electrical environment. Voltage stability, or high-low supply? Impact of other equipment? Aaron's hotel bulbs come to mind. Back EMF from an elevator or the like?
3) Use conditions, temperature, up or down orientation. Mechanical vibration? On-off frequency.
Most of my CFL bulbs are the n:vision brand, made in China They are the BR-30 type mounted upside down in IC ceiling cans which are buried in attic insulation. They are rated at 14W, equivalent to 60W IIRC. I don't have the packaging anymore, so I don't know what life they claimed when most were purchased in 2006. Most of my bulbs by far are the originals.
I have some outside too that are not outdoor rated and are lasting. They are in a normal outdoor spot/flood fixture and under a deep eave so they don't get much weather exposure.
I use a normal 75W incandescent in my well tank room for 2-3 months in winter. It gets turned on and stays on in a very dry and temperature stable condition. There is no globe enclosing the bulb, so heat will quickly dissipate. It takes two of those bulbs to get through the winter. That's about the life I expect from an incandescent.