Comment You keep using that word... (Score 2) 710
Halogen. I do not think it means what you think it means.
Halogen lights run VERY hot and bright, but do not offer any energy savings, as they are still incandescent (glowing resistor) lamps.
Do you perhaps mean fluorescent or compact-fluorescent lamps (CFL)? They are filled with low pressure mercury vapor and argon, xenon, neon, or krypton. They are about the same efficiency as LED, but are slow to come to full brightness as you describe.
Otherwise, great post. Completely agree on the advantages of LED. I've actually skipped the bulb-style and have started installing LED strips with a standalone 12vDC converter.