I'm far from experienced, but I can tell you what I've noticed so far from my Auto grow compared to my Photo grow: 26 days in, not much... They've behaved similarly to the toppings and LST. No stunting to speak of, just a couple of days of slower growth, followed by explosive growth. I experienced the same thing with the photo's. Same with defoliation, the first time it seems to slow growth for a couple of days, but then it explodes with new growth and every defoliation session after doesn't seem to bother it in the least bit.
I do think having a healthy plant, lot's of light and a good environment is key to keeping the plants going strong when you're introducing these stresses.
I'm about to pull down a big harvest soon which will give me a lot of time to experiment, and possibly fail, without worry. and I have a bunch of freebie Auto seeds to play with. Expect a thread from me where I'll try anything and everything we "shouldn't do" with Auto's to see if the stories are true.