LEDs absolutely rock for vegging...
Well, let me expound. SOME LEDs rock for vegging. I have the California Light Works 200-watt VegMaster. It has 40 5-watt LEDs tuned to the vegging spectrum. And it produces better results than T5s, with less heat.
The directions say to keep the light at least 18 inches above the plants, which is a huge convenience factor. It makes it so easy to water, train, whatever, without having to raise the light to make room for handy work, and then having to lower the light afterwards.
When I used T5s, I had to keep the fixture about 2-3 inches above the plants for good results. And this caused some heat issues. Although T5s run much cooler than MH, they still produce a fair amount of heat. Couple this with having to keep the light 2-3 inches above the plants for good results, and the benefit of LEDs become attractive.
Like I said, I just bought the California Light Words 200-watt VegMaster. It has been great so far. My plants are squat, bushy, and loving their cool but well illuminated environment. I will never go back to T5 or MH for vegging.
For flowering, HPS still rules.
My LED cost $400, and covers a 3x3 area very well. It will last without bulb changes for 2.5 years on a 24/0 veg schedule. But I can afford it, and I really like it, so I don't care how much anyone else is saving by using inferrior T5 lights.
Hope I didn't offend anyone. LEDs have arrived for vegging, performance-wise. Price-wise? Not so much. But it's worth it to me. And the price will eventually drop and completely make T5s and MH obsolete for vegging.
Naysayers, feel free to reply. But be warned in advance: you're wrong. Technology advances. And some leading LEDs are great for vegging, in every category except price. Which is a major factor for some of you, I know.
Good growing. And goodby to MH and T5s for vegging. Good riddance.