Man, I would NOT transplant/re-pot what-so-ever! There's probably a 90% or better chance you'll either put her in such a state of shock she'll probably turn Hermi on you, OR she'll simply die. Usually when those main roots get through the bottom holes you'll find that there's a tremendous (like 100:1) amount of smaller, supplemental roots that feed these main ones. I sometimes will do a "thinning" of massive, explosive roots because they do take over and utilize all that space for themselves which takes away that valuable access of getting the Oxygen to those roots. Almost every strain I have ever grown has flowered just like what you describe. In a strain that's, lets say, 8 weeks to flower 1-2 weeks the lady shoots and stretches to gain height and thus the best access to those bud sites for the pollen. She'll gain a large height increase (near 50% more), show a tendency towards more firmness in the buds as she packs more and more buds on. Then you'll notice her slow down about 1/2 way through and literally stop production. Then POW, she'll burst forth again packing more weight and Trichomes. Then the last few days she leaps one last time to try to gain one last attempt, a burst of growth for "more exposure". All this is normal as if the plant knows she isn't getting laid but tries harder just the same. Good luck to you; you'll do just fine. Don't mess with the roots unless you know exactly what to do. Life blood of the plant and you can really mess up...
I say experiments are all good with free bag seed plants 
great experience builder for free 