PBN's seem to get a bad rap because they are usually approached wrong. BB'ers need to warm up the area and take time to work on the required flexability of this exercise. Most BB'ers will tend to have a too tight shoulder girdle anyway. Take a light bar (or even a broom/mop handle) and just do warm-up/stretches of this exercise. 20 to 30 reps.Than, using a regular exercises bar, add weight slowly. Rushing the weight (using too much, to soon) can cause injury. But this can be said for most exercises anyway. Straight arm pullovers and just hanging from a overhear bar can also help to give better flexability to the shoulder region.
Holding the grip too wide can allow extra stress on the shoulder area. Try for a grip that forms about a 90 degree angle between the forearms and upper arm at the elbows. Even too close a grip may cause problems with some folks. Lower the bar to, and touch, the upper traps only. The more you do the PBN, from workout to workout, the more flexabily is gained until this exercise can feel quite natural for you. Some will lower the bar to the mid-trap range without any trouble at all. The PBN can allow for very heavy weight to be used after a while. Though pure BB'ers will require a weight with-in the moderate range. And they really do not want to lockout each rep. PL'ers will use heavy PBN's to improve their benches. Actually PBN's can strengthen the whole shoulder girdle against injury if approached correctly.
The few Pro's I have seen train, and some of the top BB'ers, usually include the PBN. But they focus on just doing middle range reps at a very fast pace. So it's more like 1/4 to 1/3 reps, never coming close to a top lockout or lower than the middle of the back of the head. Keeping the TUT at it's most intense. Good Luck.