Breathing every 4 breaths sounds like it is working for your pace. The caution is breathing every 4 strokes only on your left side. This typically causes an imbalance in your stroke. You should try breathing when you left arm is out and from your right shoulder. It will feel very strange at first but definitely a great improvement project.
If you need to be convinced, listen to Terry's recents podcast on bilateral breathing.
http://www.totalimmersion.net/blog/p...ral-breathing/