One 42 watt bulb has given a noticable difference over 2x 26 watts on a few plants in my grow room. 42 watts give a much larger margin of distance between the plant allowing it to grow without losing lumens. You are somewhat right though. A very close 42 watt compared to 2 very close 26 watts... the 26 watts would output more "Lux".yeah, the 26w with cost of splitters would be around $30