🌱 I haven't tried an LEC yet, but everyone on here who's using one seems to like it! It's like a hybrid between MH and HPS, and I believe you can use the one light from seed to harvest. I'm not sure if you might need two 315's for a 4x4, or if one would be enough. I think you could start with one, and then see if you need more.
When it came to autos and nutrients, they seemed basically the same as photoperiod plants, just a little more sensitive to high levels of nutrients. Definitely start at half strength nutrients at first! One thing that's cool about autos is most nutrient companies give you a nutrient schedule that assumes a 4 week vegetative stage, and then transitions to flowering. With photoperiod plants, you just repeat week 4 for as long as you're in the vegetative stage. With the auto you can follow the schedule exactly as is since the vegetative stage will last about 4 weeks naturally. So it's cool you can just follow the schedule week-by-week without repeating weeks or figuring anything out.
I think growing with autos may be easier than with photoperiod plants because you don't have to worry about light leaks or light schedules, BUT if they get really stunted when they're young, it will ruin your whole grow and you'll want to start over. This page has a good explanation of what a stunted auto-flowering plant looks like about halfway down the page:
http://www.growweedeasy.com/how-to-train-autoflowering-cannabis-strain If your photoperiod seedling gets stunted, you can just keep it in veg until it recovers. With an auto if it gets stunted, it will stop getting bigger so you need to start new plants to get a decent yield.
So it's really important to start the seed right and avoid overwatering. But if you give them a good environment, I feel like autos grow faster than photoperiod plants, and you get more yield in less time. My last indoor grow was autos, I'm doing photos outside right now, but my next indoor grow I think I'm going to do a bunch of autos again. It just made so much bud!
The other main thing to worry about, is if you get seeds from a untrustworthy breeder, sometimes they don't automatically start making buds, or take way too long to auto. If that happens, you have to put them on a 12/12 schedule like a photoperiod plant, and you basically lose all the benefits.
So if you do grow autos, make sure to get your seeds from a reputable breeder! I liked the autos I grew from Mephisto Genetics and Nirvana the most, but there's lots of good ones! 🌱