Re: Staying soft.
Toshu randori is the Shodokan version, 2 people trying to apply waza on each other full force and full resistance. (full force may mean different things to different people, no weapons are used in toshu)
We also have 3 versions where we have a 'designated' attacker using a (safe) tanto:-
kakari-geiko (very light, no resistance)
hikitate-geiko (uke will only allow himself to be thrown if he feels the waza is fairly good)
randori (no-one is going down for anything, uke may avoid, counter and attack at will - as may nage)