Tai chi really helps my wing chun. It disciplines me to use my body as one whole unit. If I strike my hips sync with it. Thats when you start to first notice your art to be more effective. You start to effect the wooden dummy more, foot work becomes easier and you don't have to think about it. That is the first step of learning how to control your bodies energy. I am just starting to learn this with my sifu and it will takes years of more training to develope it fully, if I can even reach that level. I can't say I have ever really released a lot of energy into one strike but I have felt a strike from someone who knows how to do it. It hurts.

WC imo is more of a nuetral art. It can utilize both external and internal techniques. So theoretically it would be wise to train in both, so then you could utilize both in your WC.