I currently have WSDL caching enabled in the store to improve client API performance. However, is there a danger to it. If I change some aspect of the store that affects the WSDL, is the client going to be continuing using the wrong WSDL file or will he/get get an updated one?
Typically you just need to log into the Magento store and flush the caches. That is by far the easiest method to ensure the latest changes are used. The cache wsdl will be a problem if you do not remember to flush the proper caches.