depends....if the rootball is loosenable then I will loosen it a bit. Sometimes you can't do that without damaging the roots especially if they are fleshy and not fibrous and in that case I won't
I think that some plants are more susceptible to root disturbance than others, therefore roots should only be teased out very gently.
Giving the pots a good soak, an hour prior to planting, I think is a good tip.