From a NON-SOF perspective, training and acclimatization as a unit is the difference between a unit being successful or a failure.
That said there will always be aspects that you cannot train a person for, generally how they initially react to fear of death, and the many of the psychological effects of combat operations (death of a friend, children being blown to bits, etc).
That's not to say you can't train people to react and ignore some aspects, but generally speaking from my personal experience, it boils down to the individual and how they process and react to particular incidents that are common on the battlefield.
Being that most SOF have some sort of selection and evaluation proccess, I would imagine these issue are not as common as they are in the CF side.