Hello Mr. Drummer...

2 - 600s used properly will almost always out grow (yield) 1 - 1000 watt bulb..

The reason why many people don't choose to go the 2 - 600's route is because it requires one to grow MORE plants and keep them shorter (SOG)... more plants = more risk

The 1000 watt bulb will have greater penetration... meaning, the plants will have more quality buds further down the plant.. This is irrelevant when growing numerous small plants..

2- 600's can cover a greater area than 1 - 1000 watt... more plants with more BIG main colas.. YEEE HAA

Now.. 2 - 1000's.. now you're talking a GREAT harvest...

iloveyou