Hi,
There is no doubt that WP Fastest cache is one of the most speedy cache plugin i ever used. Some other cache plugins (both free and premium) allow users to add multiple cdn url. Personally, I've several websites where i use several cdn urls. For example: images.mydomain.com (for images), for js/ css static.mywebsite.com.
May i know if you have any plan to add this features in future versions?