root mass can be repaired, if the plant was root bound tearing a few roots off may help... I go through this with clones that I wick water initially - just make sure not more 1/4 of the roots are damaged and you should be fine. when transplanting I usually build up the nutes before the repot, then use fresh water for the next few waterings as nutes can further damage broken roots... even though your flowering you can repot if you think the plant does not have the root mass to sustain the canopy - good rule of thumb - 1 gallon of soil per foot of the plant...
I find repoting is an excelent way to stimulate bushy growth, when the plants are small keep the pot small, as they grow repot to the next size up.... I did an experiment where I planted 2 clones after they where rooted, one in a 8 oz cup, the other in a 4 cup/1 liter pot - the one in the 8oz cup stayed short and grew just as many nodes/leaves and the one in the liter pot but that one stretched much more, even though the stem width was not that much greater....
