led growlights are still relatively new, ie. there is not a lot of information out there about them... from personal experience, nothing can outdo a hps during flower, the closest i've seen is a CMH bulb, which has mixed spectrums of hps and mh. however, you will find people on both sides of the line, its all about personal preference really...
not even close ive seen results leds good for everything but flowering hps is my preference. u could supplement a hps with led for good results
LEDS cant right now but you can grow with them. The problem is the market is flooded with cheap ones. If you read a fare amount people are having luck with them but only the really expensive ones. Why pay 500 bucks for one when you can get the same or better results outta a 400w HPS light tube that costs 150 bucks. The advantage is alot less power consumption but its like buying a Hybrid car. How much gas would you have to use to break even vs a high mpg non hybrid. It can take years. Same with LEDs. when people talk about energy savings well electricity in Atlanta is only 11 cents per KW. Would take years of use to break even The other big LED plus is hardly any heat but ventilation stuff is cheap so its another non issue to me.
I have read a lot on LED and other forms of lighting, and I highly suggest you wait for the technology to mature a little more. LED tech is almost there, but not quite. As for the question to bud tightness, I would say HPS is your best bed for greatest bud density. I am using a single 1000 watter in a 4x4 tent and its working well for me so far. Almost week seven and I have had to spike them up to keep them from falling completely over. If energy use is your game, you could always go for some lower wattage cfls, but I would still say you would want an HPS. Nothin beats it really. It even comes with the satisfaction of knowing your plants will love you (before you cut them that is)
LED can compete with HPS. It just takes a lot of them to do it, and it takes much more wattage than the marketing claims it does.