If they need it, they need it. Twas the reason for the hydration question. To some folks the ball looks rootbound, but can still hold a gallon of water. Extreme rootbound won't hold much water, and most of it ends up in the drip tray. (in case someone else is curious)

As long as you have the headroom, and add some extra perlite, 8 gal pots should be fine. Especially if in 4's and 5's already. :thumbsup:
(what lights are you using for flowering?)

Roots will keep forming, and rootbound issues may well return. Ph of the peat-based medium will dive as the buffers fade. But it's up to you. Are you afraid of the rich medium?