Ok, say I had four 26w CFLs, each 2,000 lumens. That would be a total of 104 watts and 8,000 lumens. If I have the formula correct, that would be a combined 76 lumens per watt. That is a low number, correct?
A 400 watt T5 setup would provide 40,000 lumens at 100 lumens per watt. Is the difference that significant?