i messed up with one of my plants during repotting. It is now significantly behind the other plants (all flowering).
Will the plant take longer to flower, or simply produce less?
The more roots you break or chop off the more stressed the plant will be.
That's the simpliest thing I can tell you to remember.
In Bonsai they say you can cut up o 1/2 the root system of a plant.
The plants is stressed for about 2 weeks. after that time shoot growth usually continues.
Usually after a couple of weeks the roots have grown back enough for the plant to continue shoot growth.
Remember "Roots before Shoot"
Plants in flower usually slow there root growth way down after a month or so. the plant is transitioning into flower it doesn't need to waste energy growing roots.
Yield depends on how big the plant will get. Big plants give you big yields. That's if you have a good grow with out any problems.
Good Luck on Your Grow