CFL's and MH lamps are great, and with a few exceptions thats all I use in my house. Well Ok the other one is Halogen, not MH, but their life span is also up there.
Whats wrong with considering an average of 12 hours a day of lamp useage againest your numbers gives 1.8 years and 2.2 years respectfully.
8000 hr ? 12 hr /day = 666 days
666 days ? 365 days / yr = 1.82 yr.
And I'm only running 25 Watt CFL's, 60 watt Halogens...
I bought in a long time ago in the lamp techno craze, I've bought the multi packs but the lamp will sometimes get broken before being used...