I replaced (12) 921 Bulbs with (12) 48 SMD LED Flat Panels today. They are available direct from China for $2-$4 each with shipping....
Following are the stats recorded via light meter of a double fixture at 3' in the front and 2' to the side...
3' FRONT = 166 lux
2' SIDE = 62 lux
48 SMD LED
3' FRONT = 161 lux
2' SIDE = 40 lux
COLOR = LED is slightly cooler in color
SIDE DISPERSION = 50% less (a benefit in my low ceiling TT)
HEAT = LED Fixture was warmer than expected after 1 hr - yet still cooler than incandescent bulb fixture
Overall = I'm happy.....and I know my 12V converter is happier b'cuz the fan isn't running when all the lights are on....