At November, 2012, this is the Commercial Electric box label of claimed life and energy usage.
Please compare this information, with the previous post. An estimated energy cost of $1.75 per year, at rate 11 cents per KWH, assumes operation at full power, three hours a day, 365 days, 1095 hours. This is a reasonable scenario for a home office, used only in the evening. I like my assumptions better, for a kitchen or a hallway: eight hours a day at average of full, and 20% dimmed, equal to 4.8 hours at full power, costing $2.80 per year, per light. The rate of payback is mostly a consequence of found wattage. Say found lights are incandescent, at 65 watts, costing $7.84 per year at box assumption of three hours per day, not dimmed. If the installed cost is $45, into a good, found, light can, the simple payback is 45/(7.84 - 1.75) = 7.4 years. This is still a very good 14% simple interest.
Now, what is the picture vs. box numbers, where the installation includes patch-out of an ugly non-IC can? Say the fair installed cost is $75 per light. In the payback calculation, include air sealing and insulation savings. Deduct a $10 per light cost of a cover over the can, Assume one sq ft insulation loss, at $2.4 * (1/3 + 1/41) = $.75 per year, and heat-driven infiltration for area 7.5 sq in, $4 per year. Payback = $65/(7.84 - 1.75 + .75 + 4) = six years. Payback is faster where an ugly can light is replaced, despite higher installation cost.
The payback study would be turned on its head, if the found basis is with operable CFL bulbs of same wattage, lasting as long as an LED. If in fact a CFL bulb lasts only three years, being replaced ten times in a 32 year LED life, the CFL is much poorer value. In truth, CFL's and their hazardous mercury, will not compete for many years, with LEDs. CFLs are irrelevant, and already should not be preferred over a $40 LED. Public incentives should always be directed at the lasting solution. A lasting solution is assured with the plate LED. Get rid of the incandescent bulb fixture, so a fix can't be reversed.