The two 300's is all I run. They are the "old style" 3 watt 3x100 and each draws 180 actual watts. I paid like $75.00 each back when Mars was changing over to the 5 watt leds and they were for sale at clearance prices. The new MarsHydro 5 watt 5x60 is still only a little over $100.00 I believe. I run a variable speed 220 cfm exhaust fan, and the tent being in a 75 degree room, have no trouble keeping tent temps below 85. LED's last for years, I don't know just how long, but a number of years. I start my seedlings at 30 inches and let them grow up to the light until it is about 24 inches away and leave it adjusted to 24 inches until stretch is over, then I lower down to about 12 inches from the tallest plant top. I like to have two 300's rather than one 600 as I use the two lights pointed in from two sides during LST, which is almost a requirement with a 5 ft tall tent. You can make the plants really stretch out wide growing more out, instead of up, toward the lights. Alot of all this depends on your goal as a grower. If you are attempting to grow enough medicine to last you until your next harvest, then you are in my class and something like the MarsHydro is just what you want. If you are growing for more high volume purposes, then you may need to spend some more money. You may be in the hobby class where your goal is to make every plant exhibit 100% of her genetic potential, which is what it seems we all turn into after awhile, LOL. Good luck with your grow. You will like LED, be sure to have CaMg on hand as the LED's really make them CaMg hogs. I supplement CaMg with every feeding. What medium do you grow in? Or are you DWC, always wanted to give DWC a try, but with 5 foot tall tent, the bucket takes up a lot of verticle space.
Are you new to AFN? Welcome if you are, this place is a gold mine of great growers. Go to Introductions and say hi to everyone and you will find a host of interesting people.