I am going up to the 12" container again (you know, Storm Trooper Styleee). Those hold just under 4 gallons, and these are around 1 gallon.
I do not expect them to get root bound, but we'll go with these in case they do.
Everything seems to move much slower under ground with this soil I use 1/2 the water when I water, and I water much less frequently. The males I just culled looked perfect and were no where near root bound after 1 week into flip. I love this soil.