Thinking about it from the CSS side of things, if your selectors are sufficiently generic, the most you'd need to do would be to change the name of the CSS file you're referencing in the <HEAD>. Take a look at the CSS Zen Garden for an example of how far you can go in the way of restyling a page simply by changing which CSS file you link to.
I can't see any real advantage to you the developer of inlining the CSS; if you're reusing the same CSS file, it'll end up cached in the browser; if it's inlined, you'll be transferring it every time you hot a page.