Some data, I did a little measuring, for those interested:
4' (2) tube fluorescent light fixture, tubes rated @ 40 watts each) measured: 50 watts (25 watts per tube), 215 LUX.
4' (2) tube converted to 18 watt rated LED tubes measured: 28 watts (14 watts per tube) 301 LUX
8' (2) tube High Output fluorescent light fixture, (tubes rated @ 110 watts each) measured: 220 watts (110 watts per tube) 398 LUX
8' (2) tube converted to 36 watt rated LED tubes measured: 60 watts (30 watts each) 462 LUX Note: I did not go with the high output 8' LED tubes, but rather installed new tombstones for single pin LED tubes. I didn't like the reviews of the high output ones.
All tubes mfg by Hyperikon. US Company selling (probably) import LED's. No mfg origin on the tubes or info that came with them.
LUX measured at night, and with only the light being measured turned on. Light is cumulitive, and if I flip on another light next to the one being measured, the LUX goes above 500.
Impressive lights! No more ballasts, and humming, and a substantial power savings.
Now.... if they last as long as they say.....

Bill