if you are only willing to commit 18/6 to an auto, the end result is going to suck. No matter what auto you are going to get its going to be FAST 60 - 80 days. I have found the time's for an auto are MUCH MORE accurate then the times given for photo periods. Unfortunately we are pretty early in the generations of ruderalis. So its going to be hard to find everything you want in the plant. The shortest, most potent plants i grew were: 60 day wonder, and Critical Jack. Haze automatic and Haze 2 automatic high was insane for an automatic, but some of my haze's got up to 4 - 4 1/2 feet. On the up side, the sativa high was almost untouched as far as potency.
I love riu. but you may want to browse on over to the autoflower network