I'd be interested to see what the root ball/mass looks like. I tend to transplant early, either way there are risks. I understand I could damage or shock the delicate young roots, but I think that risk always exists and my main goal is to avoid stunting the plant, which can happen if I leave it in too small a pot for too long. Your plants look very healthy, you could be in the optimum window for transplanting them (honestly, I'm not sure if I know when that is... every year I kind of wing it and mostly it turns out fine).
I grow for a heavy smoker, so I'm always looking for ways optimize production-per-plant and trying things that might enable them to get close to their full potential. That's why I've been putting them in the ground, no root limits there and I've had them get pretty big in that situation. When I do go to pots next year I'll go with 10 gallon -- it's just dirt, you never know when you'll get that pheno that can really put on weight when its roots have lots of room. I might be alone in that philosophy, most dedicated auto growers will tell you it's a complete waste to go over 5 gallons, and many say 3 is fine or even optimal. That's just not my experience.
It seems that with autos and their shorter more pre-determined lifespan, they have less recovery time than photos to "normal" shock situations like transplanting and topping. I had autos that I put outside early one year and then we had an unusually long cold spring, and some strains never recovered, they were totally stunted, others shot up as soon as it warmed up. Autos are great, but they can be less forgiving and there can be a huge variation between strains and within them.