Got my medical and set up a small grow with 4 clones from a local shop. Clones were about 12inches when I got them and its been about 2 weeks under 24 hour light. They haven't gotten a lot taller maybe 4 inches taller now but the new leaves are growing super close together. Heat was a big concern so I was forced into using a LED light for this and I was hesitant to spend the money on this one to test it out. $320 after shipping on this light 90w UFOLED. I wish I could have bought a bigger light from them. If you've never seen one the things are BRIGHT you can't even look at them. After being in the room with one for 10 minutes it messes with your eyes bright. I don't know if I can mention the company here or not but if you buy one of these lights the plants LOVE them but make sure you don't buy the cheap ones.
Never used an LED light before but im definitely looking into it. ive been told there great for vegging. but they produce super loose buds, but with enough wattage can grow the best weed ever. Your gonna want like if im right like atleast 100 watts per plant. but it may be different with LED's but if heats a huge issue, try using some 2500k cfls in the flower stage around the bottoms or something.
I'm just starting to flower them this week we'll see how it goes. If all goes well I may order the higher wattage ones I need but they are really pricey.
That 90w is not going to be enough for 4 plants. 1 or 2 would be the max. I use a 126w Hydrogrow with 2 plants and 2 cfl's. Also lst is your friend when using led. Good luck