Replaced 1/2 my 921 bulbs on my last trip. Based on research here, I got pretty close with the lumens. I have a progressive industries EMS, so was able to look at my amp usage for the incandescents vs. usage of the new LED lights.
The stats showed:
each incandescent bulb = 1 amp
each LED "corn cob" = .25 amp
So- a 75% savings in amp usage. We have many double bulb light fixtures, so...flip a light on, and 2 bulbs come on. Turn on 2 of these fixtures, and usage is 4 amps with the old bulbs, and only 1 amp with the LEDs. Pretty significant savings.