improper form on the bench can give you shoulder issues. You want to pinch your shoulder blades together and have your arms more tucked in as opposed to flared out to the side (they should form an angle closer to 45 degrees than 90 degrees with your body). You also don't want an extremely wide grip.
This is good info that you should deffinitly put into practice.
In the article below there is 2 clips, bodybuilder V powerlifter benching, and the reasoning behind it, have a look.
There's no benefit in benching 'body builder style' in comparison to power lifter style. People say body uilder style (arms flared, wider grip) will 'hit the chest more'. Whether this is true or not, it's not a benefit you would notice until you had already gained a lot of mass.
Even then, the benefit of this is at the expense of the shoulders. On top of that, powerlifter style undeniably allows you to use more weight (when done correctly) - more weight = more size? So there is benfit in powerlifter style, too, in terms of bodybuilding goals. not to mention your not beating up the shoulder half as much.
The point in my pros and cons wasn't really to start a debate, but to demonstrate that the difference in benefits is negligible (and arguable) in terms of size. One hits the chest more, one lets you use more weight. What one amounts to more size?
answer = who cares. Look after your shoulders, you only get 2 :-)