I am growing 3 (seedling at 3 weeks old) and 1 just under 2 months auto flowering plants, under 400watt. I think this is fine for the autos mainly cause they stay short. You need to keep the lights on a minimum of 18 hours a day or as much as 24. Its recommended 20. My first grow tent was kinda of small and came with all the equipment Jardin90. But got some free auto's from Attitude and gave it a try in my extra tent. I also have a Jardin120 where I am growing normal female seeds. I planted them and the auto's aprox the same time. Harvested the some other auto's that planted at the same time. And half way though another crop growing (autos) Have put my plants back in the grow tent so the bottom have can grow some more.
My point being auto's are good, for a fast turnaround.